Ex  Libris 
C.  K.  OGDEN 


ROLLO'S 

PHILOSOPHY 
[AIR.] 


THE  ROIXO  SERIES 


IS    COMPOSED    OF    FOURTEEN    VOLUMES,   TIZ 


Hollo  Learning  to  Talk. 
Rollo  Learning  to  Read. 
Rollo  at  Work. 
Rollo  at  Play. 
Rollo  at  School. 
Rollo'g  Vacation. 
Rollo'!  Experiment* 


Rollo'g  Museum. 
Rollo's  Travels. 
Rollo's  Correspondence. 
Rollo's  Philosophy— Water 
Rollo's  Philosophy— Air. 
Rollo's  Philosophy— Fire 
Rollo's  Philosophy-Sky. 


A    NEW    EDITION,    REVISED    BY    THE    AUTHOR. 

BOSTON: 
PHILLIPS,  SAMPSON,  AND  COMPANY 


Entered,  according  to  Act  of  Cotigre**,  in  the  Year  18S3,  by 

PHILLIPS,  SAMPSON,  fc   CO., 
IB  the  Clerk'i  Offict  tf  the  District  Court  of  the  Diitnct  of  Maraachuiett 


PEEFACE. 


THE  main  design  in  view,  in  the  discussions 
which  are  offered  to  the  juvenile  world,  under  the 
title  of  THE  ROLLO  PHILOSOPHY,  relates  rather  to 
their  effect  upon  the  little  reader's  habits  of  think- 
ing, reasoning,  and  observation,  than  to  the  ad- 
ditions they  may  make  to  his  stock  of  knowledge. 
The  benefit  which  the  author  intends  that  the 
reader  shall  derive  from  them,  is  an  influence  on 
the  cast  of  his  intellectual  character,  which  is  re- 
ceiving its  permanent  form  during  the  years  to 
which  these  writings  are  adapted. 

The  acquisition  of  knowledge,  however,  though 
in  this  case  a  secondary,  is  by  no  means  an  unim- 
portant object ;  and  the  discussion  of  the  several 
topics  proceeds  accordingly,  with  regularity,  upon 
a  certain  system  of  classification.  This  classifica- 
tion is  based  upon  the  more  obvious  external  prop- 
erties and  relations  of  matter,  and  less  upon  those 

2000175 


6  PREFACE. 

which,  though  they  are  more  extensive  and  gen- 
eral  in  their  nature,  and,  therefore,  more  suitable, 
in  a  strictly-scientific  point  of  view,  for  the  foun- 
dations of  a  system,  are  less  apparent,  and  require 
higher  powers  of  generalization  and  abstraction ; 
and  are,  therefore,  less  in  accordance  with  the 
genius  and  spirit  of  the  Rollo  philosophy. 

As  teachers  have,  in  some  cases,  done  the 
author  the  honor  to  introduce  some  of  the  pre- 
ceding works  of  this  class  into  their  schools,  as 
reading  books,  &c.,  considerable  reference  has 
been  had  to  this,  in  the  form  and  manner  of  the 
discussion,  and  questions  have  been  added  to  facil- 
itate the  use  of  the  books  in  cases  where  parents 
or  teachers  may  make  the  reading  of  them  a  regu- 
lar exercise  of  instruction. 


CONTENTS. 


CHAPTER  I. 
LOST  IN  THE  SHOW, 


CHAPTER  II. 
FLYING,  ..........................................  19 

CHAPTER  III. 
VALVE  MAKING  ..................................  40 

CHAPTER  IV. 

Exi'ER'M  JENTS,  ....................................    51 

CHAPTER  V. 
PRESSURE,  .......................................  64 

CHAPTER  VI 
BALLOONING,  .....................................  79 

CHAPTER  VII. 
PHILOSOPHICAL  DISCUSSION.  ..............  .....  .....  94 


CONTENTS. 


CHAPTER  VIII.  Pag, 

TASKS, 108 

CHAPTER  IX. 
BURNING, 121 


CHAPTER  X. 
GRAVITATION, 143 

CHAPTER  XI. 
AIR  IN  MOTION, 158 

CHAPTER  XIL 
Ant  AT  RXIT, 178 


THE 


HOLLO   PHILOSOPHY 


AIR. 

CHAPTER    1. 
LOST  IN  THE   SNOW. 

ONE  pleasant  morning,  very  early  in  the 
spring,  Hollo's  cousin  Lucy  came  to  call  for 
Rollo  to  go  on  an  expedition,  which  they 
had  planned  the  day  before.  It  was  near  the 
end  of  March,  and  the  snow  had  become  so 
consolidated  by  the  warm  sun  in  the  days, 
and  the  hard  frosts  at  night,  that  it  woud 
bear  the  children  to  walk  upon  it.  The 
children  called  it  the  crust ;  but  it  was  not, 
strictly  speaking,  a  crust,  for  the  snow  was 
compact  and  solid,  not  merely  upon  the  top, 
but  nearly  throughout  the  whole  mass,  down 
to  the  ground. 


to 


Rollo  and  Lucy  were  going  to  have  an  ex- 
pedition upon  the  crust.  Rollo  had  a  sled, 
and  they  were  going  to  put  upon  the  sled 
such  things  as  they  should  need,  and  Rollo 
was  to  draw  it,  while  Lucy  and  Nathan, 
Rollo 's  little  brother,  were  to  walk  along  by 
his  side. 

Rollo's  sled  was  ready  at  the  back  door, 
when  Lucy  came.  Lucy  brought  with  her 
some  provisions  for  a  luncheon,  in  a  basket. 
This  was  her  part  of  the  preparation.  Rollo 
got  his  axe,  and  one  or  two  boards  a  little 
longer  than  the  sled,  which  he  said  were  to 
make  seats.  He  also  had  a  tinder-box,  and 
some  matches,  to  enable  him  to  make  a  fire. 
When  all  things  were  ready,  the  three  children 
set  out  together. 

Rollo  drew  the  sled,  with  the  boards, 
the  basket,  and  some  other  things  upon  it, 
all  bound  together  securely  with  a  cord. 
The  load  appeared  to  be  considerable  in 
bulk,  but  it  was  not  heavy,  and  Rollo  drew 
it  along  very  easily.  They  were  not  obliged 
to  confine  themselves  to  the  roads  and  paths, 
for  the  snow  was  hard  in  every  direction, 
and  they  could  go  over  the  fields  wherever 
they  pleased.  In  one  place,  where  the  snow 


LOST    IN    THE    SNOW.  11 

was  very  deep  on  the  side  of  a  hill,  they 
went  right  over  the  top  of  a  stone  wall. 

It  was  a  cloudy  day,  but  calm.  This  was 
favorable.  The  sky  being  overcast,  kept 
the  sun  from  thawing  the  snow ;  but  yet 
their  father  told  them  that  probably  it 
would  begin  to  grow  soft  before  they  came 
home,  and,  if  so,  they  would  have  to  come 
home  in  a  certain  sled  road,  which  Jonas  had 
made  that  winter  by  hauling  wood.  He  ad- 
vised them  not  to  encamp  at  any  great  dis- 
tance from  the  sled  road. 

They  came  at  last  to  a  pleasant  spot  on 
the  margin  of  a  wood,  near  where  there  was 
a  spring.  The  rocks  around  the  spring  were 
all  covered  with  snow,  and  the  little  stream, 
which  in  summer  flowed  from  the  spring,  was 
frozen  and  buried  up  entirely  out  of  sight. 
But  the  spring  itself  "was  open,  which  Rollo 
said  was  very  fortunate,  as  they  might  want 
some  water  to  drink. 

Here  they  encamped.  Rollo  cut  some 
stakes,  which  he  drove  down  into  the  snow, 
and  contrived  to  make  a  rude  sort  of  table 
with  his  boards.  He  also  cut  a  large  number 
of  hemlock  branches,  which  Lucy  and  Nathan 
dragged  out  and  spread  around  the  table  for 


12  UK. 

them  to  sit  upon  Then  Hollo  built  a  fire 
of  sticks,  which  he  gathered  in  the  wood. 
The  ground  was  covered  with  snow,  so  that 
it  would  have  been  very  difficult  for  him  to 
have  found  any  sticks,  were  it  not  that  some 
kinds  of  trees,  in  the  woods,  have  a  great 
many  small  branches  near  the  bottom,  which 
are  dead  and  dry.  These  Rollo  cut  off,  and 
Lucy  and  Nathan  dragged  them  out,  and  put 
them  on  the  fire  when  he  had  kindled  it. 
The  fire  was  a  little  way  from  the  table, 
with  the  carpet  of  hemlock  boughs  between. 

There  was  a  high  hill  covered  with  snow 
at  a  little  distance,  and,  after  they  had  eaten 
their  luncheon,  Rollo  said,  — 

"  O  Lucy,  we  will  play  go  up  the  moun- 
tains. There  is  a  hill  for  us.  That  shall  be 
Chimborazo." 

"  Well,"  said  Lucy,  "  if  you  will  cut  us 
some  long  staves." 

Accordingly  Rollo  went  into  the  wood, 
and  selected  some  tall  and  slender  young 
trees,  about  an  inch  in  diameter,  and  cut  two 
for  Lucy,  two  for  Nathan,  and  two  for  him- 
self. These  he  trimmed  up  smoothly,  and 
each  of  the  children  took  one  in  each  hand. 
They  played  that  Rollo  was  the  guide,  and 


LOST    IN    THE    SNOW.  13 

Lucy  was  the  philosopher.  Nathan  was  the 
philosopher's  servant.  Rollo  conducted  them 
safely  to  the  summit ;  but  just  after  they  got 
there,  it  began  to  snow. 

The  snow  descended  in  large  flakes,  and 
Rollo  was  delighted  to  see  it;  but  Lucy 
seemed  a  little  anxious.  She  said  that,  if 
there  should  be  much  snow,  it  would  make 
it  hard  for  Nathan  to  get  home,  and  she 
thought  that .  they  had  better  go  down  the 
mountain  immediately,  and  set  out  for  home. 
Rollo  was  rather  unwilling  to  go,  but  he 
allowed  himself  to  be  persuaded,  and  so  they 
all  came  down  the  mountain  together. 

They  packed  up  their  things  as  quick  as 
they  could,  leaving  the  fire  to  burn  itself  out, 
only  Rollo  first  piled  on  all  the  hemlock 
branches, — which  made  a  great  crackling. 
The  snow  began  to  fall  faster.  The  air  was 
full  of  the  large  flakes,  which  floated  slowly 
down,  and  lodged  gently  upon  the  old  snow. 

The  children  went  along  very  successfully 
for  some  time,  but  at  length  Rollo  lost  his 
way.  The  air  was  so  full  of  snow-flakes, 
that  he  could  see  only  a  very  little  way 
before  him;  and  the  old  snow  covered  the 
ground,  so  as  to  hide  all  the  old  marks,  and 


14  AIR. 

to  alter  the  general  aspect  of  the  fields  so 
much,  that  Rollo  was  completely  lost.  He, 
however,  did  not  say  anything  about  it,  but 
wandered  on,  Lucy  and  Nathan  wondering 
all  the  while  why  they  did  not  get  home ; 
until  "at  length  they  came  across  a  track  in 
the  snow. 

"O!  see  this  track,"  said  Rollo.  "Here 
is  a  track,  where  somebody  else  has  been 
along  with  a  sled." 

"  Yes,"  said  Lucy,  "  some  boys,  who  have 
gone  out  to  slide,  perhaps." 

The  track  was  partly  obliterated  by  the 
snow  which  had  fallen  upon  it  since  the 
boys  that  made  it  had  gone  along.  Rollo 
wondered  whose  track  it  could  be.  He  said 
that  he  thought  it  very  probable  it  was 
Henry's.  Lucy  thought  that  it  might  be 
the  track  of  some  children,  that  had  gone 
out  to  find  them. 

"  At  any  rate,"  said  Rollo,  "we  will  follow 
the  track  a  little  way,  and  see  what  it  leads 
to.  Perhaps  we  shall  overtake  the  boys." 

Accordingly  Rollo  turned  along  in  the 
track,  but  Lucy  stopped. 

"  No,  Rollo,"  said  she,  "  we  must  go  the 
other  way  if  we  want  to  find  the  boys ;  — 


LOST    IN    THE    SNOW.  15 

the  track  is  going  the  other  way.  But 
never  mind,"  she  added,  "  I  don't  want  to 
find  the  boys ;  I  want  to  go  home ;  so  we 
will  go  this  way." 

Rollo  went  on,  secretly  pleased  to  find  the 
track,  for  he  supposed  that  by  retracing  it,  as 
he  was  doing,  it  would  lead  him  back  home. 
He  had,  however,  a  great  curiosity  to  know 
who  .could  have  made  it ;  and  in  fact  the 
mystery  was  soon  unraveled. 

For,  after  following  the  track  a  short 
distance,  they  saw  before  them  a  large,  dark 
spot  upon  the  snow,  and,  on  drawing  near  to 
it,  to  see  what  it  was,  they  found  it  was  the 
place  of  their  own  encampment ;  and  the 
track  which  they  were  following  was  their 
own  track,  leading  them  back  to  the  moulder- 
ing remains  of  their  own  fire.  They  had 
gone  round  in  a  great  circle,  and  come  back 
upon  their  own  course.  Rollo  looked  ex- 
ceedingly blank  and  confused  at  this  unex- 
pected termination  of  the  clew,  which  he 
had  hoped  was  to  have  led  him  out  of  his 
difficulty.  What  he  was  to  do  now,  he  did 
not  know. 

The  fact,  however,  that  they  were  lost, 
was  no  longer  to  be  concealed;  and  Lucy 


16 


proposed  that  they  should  go  into  the  woods, 
where  the  tops  of  the  trees  would  act  as  a 
sort  of  umbrella,  to  keep  the  snow  from 
falling  upon  them,  and  wait  there  until  it 
stopped  snowing  ;  and  then  the  air  would  be 
clear,  and  they  could  find  their  way  out. 

"  O,"  said  Rollo,  "  I  can  easily  make  a  hut 
of  hemlock  branches,  and  we  can  go  into 
that  for  shelter." 

"  But,  Rollo,"  said  Nathan,  "  how  do  you 
know  but  that  it  will  snow  all  day  ?  We 
can't  stay  in  the  woods  all  day." 

"No,"  said  Rollo;  "when  it  snows  in 
great  flakes,  it  is  not  going  to  snow  long. 
Jonas  told  me  so." 

So  the  children  went  into  the  woods,  and 
Rollo  be^an  to  make  his  hut;  but  he  was 
soon  interrupted,  and  the  attention  of  all  the 
children  was  called  off  by  a  little  bird,  which 
they  saw  there,  hopping  about,  and  appear- 
ing benumbed  with  cold.  After  some  effort, 
Rollo  succeeded  in  catching  her  in  his  cap. 

"  We'll  carry  her  home,"  said  Nathan ; 
"we'll  carry  her  home,  and  show  her  to 
mother." 

"  Yes,"  said  Rollo,  "  I'll  carry  her  in  my 
cap." 


LOST    IN    THE    SNOW.  17 

"  No,"  said  Lucy,  "  you  must  have  your 
cap  on  your  head,  or  you  will  take  cold. 
Let  me  carry  her  in  my  hands." 

"No,"  said  Hollo,  "  you  will  have  to  lead 
Nathan.  I'll  tell  you  what  we  will  do. 
We  will  put  her  into  the  basket,  for  a  cage." 

Lucy,  on  the  whole,  liked  this  plan,  and 
they  accordingly  put  the  bird  in  the  basket, 
and  Hollo  contrived  to  make  a  cover  of 
boughs,  to  keep  her  from  getting  away. 

By  the  time  that  this  was  all  arranged,  the 
children  found,  to  their  great  satisfaction, 
that  it  had  ceased  snowing  ;  and  they  imme- 
diately set  out  for  home.  Rollo  drew  the 
sled,  with  the  basket  and  bird  upon  it, 
secured  as  before  with  the  cord ;  and  Lucy 
led  Nathan.  They  now  had  no  difficulty  in 
finding  their  way,  and  soon  reached  home  in 
safety. 

They  kept  the  bird  until  the  next  day, 
and  then,  as  it  was  mild  and  pleasant,  they 
let  her  fly  away. 


QUESTIONS. 

By  what  process  had  the  snow  become  hardened  at  this 
time  ?     Did  Hollo's  father  expect  that  it  would  continue 
a*  2* 


18  AIR. 

hard  till  noon  ?  Why  not?  Did  it  continue  hard  ?  What 
prevented  its  melting  .••  How  did  Rollo  get  sticks  for  his 
fire  ?  What  name  did  he  give  to  the  hill  which  they  as 
cended  ?  What  occasioned  the  difficulty  in  the  way  of 
Hollo's  finding  his  way  home  ?  What  conversation  took 
place  when  he  found  the  track  ?  Was  this  track  in  the 
new  snow,  or  in  the  old  snow  ?  How  had  it  become  partly 
obliterated  ?  How  did  they  carry  the  bird  home? 


CHAPTER    II. 
FLYING. 

NATHAN  became  very  much  interested  in 
the  bird,  and  that  evening,  as  his  father  was 
sitting  by  the  fire,  with  a  book  in  his  hand, 
which  he  had  been  reading,  Nathan  came  up 
to  him,  and  said,  — 

"Father,  are  you  busy  now, — thinking, 
or  anything  ? " 

"  No,"  said  his  father. 

"  Because,"  said  Nathan,  "  if  you  are  not, 
I  want  to  read  you  something  out  of  my 
little  book." 

So  Nathan's  father  took  him  up  into  his 
lap,  and  Nathan  opened  his  little  book,  and 
began  to  read  as  follows :  — 

« '  With  fins  for  the  water,  and  winga  for  the  air, 
And  feet  for  the  ground,  I  could  go  everywhere.' 

"  Isn't  that  funny  ?  "  said  Nathan. 
"  Rather  funny,"  said  his  father. 


20  AIU. 

"  I  wish  1  had  wings,"  said  Nathan. 

"  Why  ?  "  said  his  father. 

"  Why,  then  I  could  fly." 

"That  is  not  certain,"  said  his  father. 
"  There  are  two  difficulties  which  prevent 
boys  from  flying.  One  is,  they  have  no 
wings;  and  the  other  is,  they  have. not 
strength  to  use  them." 

"O  father,"  said  Nathan,  "I  could  use 
them;  I  am  pretty  strong.  I  can  wheel 
Hollo's  wheelbarrow." 

His  father  smiled.  "  Very  possibly,"  said 
he  ;  "  but  I  do  not  think  that  you  would  be 
strong  enough  to  use  wings,  even  if  you  had 
them." 

"  Why,  at  any  rate,  I  am  stronger  than  a 
bird,"  said  Nathan. 

"  Yes,"  said  his  father,  "  you  have  more 
actual  strength  than  a  bird,  but  not  more  in 
proportion  t«  your  size.  You  are  absolutely 
stronger,  but  not  relatively." 

"  What  do  you  mean  by  that  ? "  said 
Nathan. 

"  Why,  you  have  actually  more  strength 
than  a  bird,  —  a  robin,  for  instance ;  you 
could  hold  him  so  that  he  could  not  get 
away ;  and  you  could  lift  more  than  he  could 


FLYING.  21 

too.  But  then  you  are  a  great  deal  larger, 
and  you  are  not  as  much  stronger  than  he  is, 
as  you  are  larger.  If  you  are  a  hundred 
times  as  heavy  as  he,  you  are  not  a  hundred 
times  as  strong.  That's  what  I  mean  by 
saying  that  you  are  absolutely  stronger,  but 
not  relatively.  That  is,  you  are  not  as  many 
times  stronger,  as  you  are  larger  and  heavier. 
You  are  absolutely  stronger,  but  not  rela- 
tively ;  that  is,  in  proportion  to  your  size 
and  weight. 

"  Now  I  can  prove  to  you,"  continued  his 
father,  "  that  you  would  not  be  strong 
enough  to  fly  with  wings,  even  if  you  had 
them.  Suppose  there  was  a  pole  fastened 
across  the  room,  and  another  pole  just  above 
it ;  could  you  pull  yourself  up,  from  one  pole 
to  the  other,  by  your  hands  alone,  without 
touching  your  feet  ?  —  Or  a  ladder,"  continued 
his  father.  —  "it  will  be  better  to  suppose  a 
ladder.  Now,  if  there  was  a  ladder  leaning 
up  against  a  building,  could  you  climb  up 
on  the  under  side  by  your  hands,  drawing 
yourself  up,  hand  over  hand,  without  touch- 
ing your  feet  ? " 

Here  Hollo,  who  was  reading  in  a  little 


22  AIR. 

chair  at  the  back  part  of  the  room,  when  his 
father  first  commenced  the  conversation  with 
Nathan,  but  who  had  been  listening  for  a 
few  minutes  past  to  what  his  father  had  been 
saying,  jumped  up,  and  came  across  the  room 
to  his  father,  and  said,  — 

"  Yes,  sir,  yes,  sir ;  I  can.  I  have  done 
it  often  in  the  barn." 

"  How  high  up  could  you  go  ? "  said  his 
father. 

"  O,  almost  up  to  the  loft,"  said  Hollo. 
"  Only,  you  see,  father,  the  rounds  are  too  far 
up.  I  can't  reach  up  very  well.  If  they 
were  nearer  together,  I  could  climb  up  so, 
very  well." 

"  Well,"  said  his  father,  "  a  bird,  when 
flying,  has  to  climb  up  in  much  the  same 
way.  He  has  to  pull  himself  up  by  the  air, 
with  his  wings,  just  as  you  do  with  your 
hands  and  arms,  by  the  rounds  of  the  ladder  ; 
only  the  air  is  not  fixed,  like  the  ladder,  but 
constantly  gives  way  under  his  wing ;  and 
so,  to  make  the  case  the  same,  you  must 
suppose  that  the  ladder  is  not  firm,  but  is 
floating  in  the  air,  and  sinks  down  with 
yom  weight,  so  that  you  have  to  climb  up 


23 


faster  than  you  pull  the  ladder  down.  Do 
you  think  you  would  have  strength  enough 
in  your  arms  to  do  that  ?  " 

Hollo  and  Nathan  looked  very  much  in- 
terested in  what  their  father  was  saying,  but 
they  both  admitted  that  they  could  not 
climb  up  such  ladders  as  those. 

"  The  air,"  added  their  father,  "  gives  way 
continually  under  the  birds'  wing ;  and  yet 
they  have  to  pull  themselves  up  by  it.  And 
this  is  very  hard.  They  must  either  have 
very  large  wings,  and  prodigious  strength  to 
use  them,  so  as  to  pull  upon  the  air  with 
very  hard  and  heavy  strokes,  or  else,  if  they 
have  small  wings,  they  must  have  strength 
to  strike  very  quick  and  often  with  them. 

The  wings  of  sparrows  move  so  quick, 
that  you  cannot  count  the  strokes ;  and 
those  of  humming-birds,  which  are  smaller 
still,  so  fast  that  you  cannot  see  them.  They 
make  a  hum." 

"  I  could  make  my  wings  go  so  fast,"  said 
Nathan  ;  and  he  began  to  imitate  the  flapping 
of  the  wings  of  a  bird,  with  his  arms,  as 
rapidly  and  forcibly  as  he  could. 

"  So  can  I,"  said  Rollo  ;  and  he  made  the 


24 


same  motions.  *  That  is  as  fast  as  crows' 
wings  move,  when  they  are  flying." 

"  Yes,"  said  his  father,  "  crows  move  their 
wings  as  fast  as  that,  whereas  you  only  move 
hands  and  arms.  If  you  had  great  wings,  as 
long,  in  proportion,  as  the  crows,  you  could 
not  move  them  so  fast." 

"  How  large  would  they  be  ?  "  said  Hollo. 

"  O,  I  don't  know,  —  perhaps  as  big  as  the 
top  of  the  dining-table." 

"O  father,"  said  Hollo,  "I  don't  think 
they  would  be  as  big  as  that.  The  crow's 
wings  are  not  longer  than  his  body,  and  so 
mine  would  not  be  longer  than  my  body." 

"  Perhaps  you  never  saw  a  crow's  body," 
said  his  father.  "  His  feathers  and  his  tail, 
which  are  very  light,  swell  out  his  body,  and 
make  it  appeaf  much  larger  than  it  really  is. 
I  presume  his  wings,  when  they  are  spread, 
are  twice  or  three  times  as  long  as  his  body. 
If  you  had  wings  in  proportion,  it  would  be 
with  the  utmost  difficulty  that  you  could  use 
them  at  all.  You  certainly  could  not  strike 
the  air  with  them  fast  enough  to  pull  your- 
self up  by  them." 

"  I   did   not  think    that  the  birds  pulled 


25 


themselves  up  by  the  air,"  said  Nathan.  "•! 
did  not  know  that  the  air  was  anything 
rea/." 

"O  yesj  it  is  something  real,"  said  his 
father. 

"  I've  seen  birds  fly  without  moving  their 
wings  at  all,"  said  Rollo. 

''Yes,"  said  his  father,  "and  so  have  I 
seen  a  stone." 

"  A  stone  !  "  repeated  Rollo. 

"  What,  a  stone  fly  ?  "  said  Nathan. 

*•"  Yes,"  replied  his  father  ;  "  did  you  never 
see  a  stone  fly  through  the  air,  without  any 
wings  at  all?  " 

"  Why,  yes,"  said  Rollo,  "  when  somebody 
threw  it." 

"  Very  well,"  said  his  father.  "  If  you  set 
the  stone  in  motion,  it  will  continue  in  mo- 
tion for  some  time,  without  any  wings ;  and 
so  will  a  bird." 

"  But,  father,  they  don't  throw  birds,"  said 
Nathan  ;  and  he  laughed  aloud  at  such  an 
idea. 

"  Birds  throw  themselves,"  said  his  father; 

'  that  is,  they  strike  their  wings  upon  the  air, 

hard  and  quick,  and  thus  get  into  very  quick 

motion,  and  then  they  can  keep  their  wings 

b  3 


Btil.  for  a  time,  and  go  on,  as  long  as  the 
impulse  they  have  given  them  lasts.  This 
shows  what  prodigious  strength  they  have  in 
their  wings.  They  can  not  only  strike  the 
air  hard  and  frequently  enough  to  raise  them- 
selves up,  and  move  along,  but  they  can  do 
it  so  easily,  as  to  get  such  a  velocity,  that 
they  can  rest  their  wings  for  some  time,  and 
sail  away  through  the  air,  only  expending 
the  impulse  they  had  accumulated." 

Hollo  and  Nathan  were  silent.  Hollo  was 
thinking  how  he  had  seen  the  swallows  sail- 
ing swiftly  round  and  round  in  the  air,  with 
their  wings  spread  out  motionless  by  their 
side. 

"  So,  you  see,"  continued  his  father,  "  the 
difficulty  in  the  way  of  a  boy's  flying,  is  not 
the  want  of  wings,  but  the  want  of  strength 
to  use  them.  It  would  be  very  easy  to 
make  wings." 

"  Would  it  ?  "  said  Nathan. 

"  Yes,"  said  his  father.  "  At  least  it  would 
not  be  very  difficult.  Ingenious  mechanics 
would  soon  find  out  modes  of  making  some- 
thing to  answer  the  purpose  of  wings,  to 
strike  upon  the  air,  if  there  was  the  necessary 
power  to  work  them.  The  great  difficulty 


FLYING.  27 

in  almost  all  cases  in  mechanics  is,  in  getting 
the  power ;  there  is  very  little  difficulty  in 
applying  it  to  any  purpose  it  is  wanted  for. 
So,  you  see,  next  time,  Nathan,  when  you 
want  to  fly,  you  must  wish,  not  that  you 
had  wings,  but  that  you  were  strong  enough 
to  use  them." 

"Well,  father,"  said  Rollo,  "men  are 
strong  enough  to  paddle  themselves  along 
in  the  water  ;  why  can't  they  in  the  air  ? " 

"  Because,"  said  his  father,  "  water  supports 
them  by  its  buoyancy,  arid  they  have  nothing 
to  do  but  to  move  themselves  along  upon  it. 
But  air  cannot  support  them  ;  and,  of  course, 
a  great  part  of  the  effort  which  they  would 
make,  would  be  required  to  keep  them  up. 
And  then,  besides,  the  water  is  generally 
nearly  at  rest,  but  the  air  is  generally  in  a 
state  of  rapid  motion." 

"Why,  father,"  said  Rollo,  "I'm  sure 
water  is  sometimes  in  rapid  motion.  The 
rivers  run  very  swiftly,  often." 

"  Yes,"  replied  his  father ;  "  but  then,  when 
they  do,  men  cannot  paddle,  or  row  boats  upon 
them.  A  current  that  should  run  at  the  rate 
of  four  or  five  miles  an  hour,  would  be  very 
hard  to  row  against.  But  the  air  is  seldom 


28  AIR. 

in  a  state  of  less  motion  than  that.  It  is 
very  often  moving  at  the  rate  of  fifteen  or 
twenty  miles  an  hour ;  sometimes  sixty.  So, 
you  see,  there  is  a  double  reason  why  men 
cannot  fly  in  the  air,  as  well  as  paddle  on  the 
water." 

"  If  we  were  only  light  enough,"  said 
Rollo,  "  to  float  in  the  air,  then  we  could  fly/' 

"  We  could  paddle  about  in  it,  when  it  was 
calm,"  replied  his  father,  "but  that  would 
not  be  flying." 

"Is  there  anything  light  enough  to  float 
in  the  air?  "  said  Rollo. 

"  No,"  said  his  father,  "  I  don't  think  of 
any  visible  substance  that  is." 

"  What  do  you  mean  by  visible  sub- 
stance ? "  said  Nathan. 

"  Why,  anything  that  you  can  see,"  re- 
plied his  father.  "  There  are  some  other 
kinds  of  air,  which  are  lighter  than  common 
air,  but  there  is  nothing  else,  so  far  as  I 
know." 

"Why,  father,  there  ar-j  clouds.  They 
float,  and  they  are  visible,  I  am  sure." 

"  Yes,"  said  his  father.  "  There  is  some 
mystery  about  the  floating  of  clouds.  I  don't 
fully  understand  it.  Clouds  are  formed  of 


small  globules  or  little  balls  of  water ;  and 
water,  I  should  think,  whatever  the  size  of 
the  little  drops  might  be>  would  be  heavier 
than  air.  And  yet  they  seem  to  float.  If 
they  are  large,  like  rain  drops,  they  fall 
quickly  to  the  ground.  If  they  are  small, 
like  mist,  they  fall  slowly.  That  I  should 
expect.  If  they  are  finer  still>  like  vapor  or 
fog,  I  should  think  that  they  would  fall  still 
more  slowly ;  but  still  I  should  suppose  that 
they  would  descend.  But  they  do  not  ap- 
pear to  descend  f  they  seem  to  float,  nearly 
at  rest ;  though  perhaps  all  the  clouds  we 
see,  may  be  slowly  descending  all  the  time, 
while  we  do  not  perceive  it." 

"  The  smoke  goes  up  from  the  top  of  the 
chimney,"  said  Rollo, 

"  Yes,"  said  his  father,  "  there  is  no  diffi- 
culty about  that.  The  vapor  from  a  fire  is 
carried  up  by  the  warm  air,  no  doubt.  Air 
swells  when  it  is  heated,  and  so  becomes 
lighter,  and  rises ;  and  the  hot  air  from  the 
top  of  the  chimney  carries  the  vapor  up  with 
it,  no  doubt.  After  it  rises  a  little  way,  and 
becomes  cool,  it  ceases  to  ascend,  but  floats 
away  horizontally.  Perhaps  it  .begins  to 
descend  when  it  gets  cool,  though  very 
3* 


30 


slowly;  and  perhaps  all  clouds  are  really 
descending  all  the  time,  though  too  slowly 
for  us  to  perceive  the  motion/' 

"Only,"  said  Rollo,  "after  a  little  time, 
thay  would  get  down  to  the  ground." 

"  Perhaps  not,"  said  his  father  ;  "  for,  when 
they  get  down  nearer  the  earth,  where  it  is 
warm,  they  may  be  gradually  dissolved,  and 
disappear,  and  thus  never  reach  the  earth.  I 
should  think  they  would  descend,  being 
composed  of  globules  of  water,  which,  how- 
ever small,  must,  I  should  think,  be  heavier 
than  air." 

"  A  soap  bubble  will  float  in  the  air,"  said 
Rollo. 

"  I  never  saw  one  that^would,"  said  his 
father,  "unless  it  got  into  a  current,  which 
carried  it  up.  A  soap  bubble  —  make  it  ever 
so  thin  —  shows  a  tendency  to  descend,  unless 
you  put  it  out  in  the  open  air,  where  there 
are  currents  to  carry  it  up.  It  descends  very 
slowly,  but  'still  it  descends.  It  is  heavier 
than  the  air.  I  am  not  absolutely  certain, 
but  I  believe  there  is  no  visible  substance 
that  is  lighter  than  the  air;  and  it  is  very 
well  for  us  there  is  not." 

"  Why,  father  ?  "  said  Rollo. 


31 


"  Because,  if  there  were  any,  they  would 
immediately  rise  from  the  earth,  and  float 
upwards,  till  they  got  up  where  the  air  was 
so  light  and  thin,  that  they  could  not  go  up 
any  higher." 

"  And  so,"  said  Hollo,  "  we  should  lose 
them." 

"  That  would  not  be  all,"  said  his  father. 
"  They  would  float  about,  above  us,  and,  if 
there  were  enough  of  them,  they  would  form 
a  perpetual  cloud  over  our  heads,  to  keep  out 
the  sun,  and  to  make  the  world  dark  and 
gloomy.  There  seems  to  have  been  no  way 
to  keep  all  the  solid  and  visible  substances 
of  the  earth  down  upon  its  surface,  but  to 
make  them  all  heavier  than  the  air. 

"And  thus,"  continued  his  father,  "all 
solid  substances  being  heavier  than  the  air, 
they  sink  in  it,  like  stones  or  iron  in  water. 
Only  those  that  are  very  much  expanded  in 
surface,  sink  very  slowly,  and  sometimes 
almost  seem  to  float." 

"  What  do  you  mean  by  expanded,  father  ?  " 
said  Nathan. 

"  Spread  out,"  said  his  father.  "  An  um- 
brella, foT  example,  when  it  is  spread  out.  is 
said  to  be  expanded  ;  other  things  are  ex- 


32  AIR. 

panded  in  a  little  different  way.  A  feathei 
is  expanded,  that  is,  it  is  spread  out  in  fine 
filaments,  which  extend,  in  every  direction, 
into  the  air,  all  around  the  stem  of  it. 
Things  that  are  expanded  take  a  great  deal 
of  air  with  them  when  they  descend>  and  so 
can  only  descend  slowly." 

"  And  water  is  expanded  in  a  soap  bubble," 
said  Rollo. 

"  Yes,"  replied  his  father,  "  and  there  is  a 
great  deal  of  air  included  in  it,  which  all  has 
to  be  brought  down  when  the  bubble  itself 
descends.  And  thus,  you  see,  the  bubble 
must  descend  slowly.  Water  is  expanded, 
too,  in  clouds ;  for,  in  that  case,  it  is  divided 
into  millions  of  small  particles,  by  which  it 
is  spread  out  over  a  great  deal  of  air,  and 
cannot  descend  without  bringing  a  large 
portion  of  the  air  with  it.  Men-  have  con- 
trived, on  this  principle,  to  make  an  apparatus 
to  prevent  being  hurt  by  falling  from  great 
heights." 

"What  is  it?"  said  Rollo. 

"  Why,  it  is  called  a  parachute.  It  is  a  sort 
of  umbrella ;  in  fact,  it  is  an  unbrella.  only 
made  very  large.  It  is  folded  up,  and  fas- 
tened under  a  balloon,  just  over  the  car,  which 


the  man  is  in.  Then,  if  the  balloon  bursts, 
or  any  other  accident  happens  to  it,  and  the 
man  begins  to  fall,  the  parachute  opens  and 
spreads,  and  then  the  man  falls  very  slowly. 
The  reason  is,  that  the  parachute  takes  hold 
of  a  large  mass  of  air,  and  brings  it  down 
with  it ;  and  so  it  cannot  descend  very  fast." 

A  few  days  after  this,  Nathan  said  to  Hollo, 
as  they  were  playing  in  the  yard,  that  he 
wished  that  he  had  a  parachute. 

"  I  know  where  there  is  one,"  said  Hollo. 

"  A  parachute,"  said  Nathan ;  "a  real  para- 
chute ? " 

"  Yes,"  said  Rollo,  "  or,  what  is  the  same 
thing,  a  great  umbrella." 

"  Is  that  just  the  same  ?  "  said  Nathan. 

"  Yes,"  said  Rollo  ;  "  for  father  said  that  a 
parachute  was  in  fact  only  a  large  umbrella ; 
and  father  has  got  a  large  umbrella  in  the 
closet,  and  I  have  a  great  mind  to  go  and  get 
it  for  a  parachute." 

"  But  you  haven't  got  any  balloon,"  said 
Nathan. 

"  O,  no  matter  for  that,"  said  Rollo; 

"  Then  how  are  you  going  to  get  up  into 
the  air  ?  "  risked  Nathan. 


34  AIR. 

"  Why,  I  can  climb  up  on  the  shed,  and 
jump  off  that,  and  hold  the  umb/ella  over 
my  head." 

Just  at  this  moment,  Hollo's  cousin  James 
came  into  the  yard,  and  Rollo  ran  to  him,  to 
explain  to  him  about  the  parachute.  After 
describing  to  him  the  construction  of  it,  and 
its  use  by  men  who  go  up  in  balloons,  he 
said  he  was  going  to  get  his  father's  um- 
brella, which  would  make  an  excellent 
parachute. 

"  And  then,"  continued  he,  "  I  am  going 
to  get  upon  some  high  place,  and  jump  off, 
and  hold  the  parachute  over  my  head,  and 
then  I  shall  come  down  as  light  as  a  feather." 

"  O  Rollo,"  said  James,  "  I  don't  believe 
you  will." 

"  Yes  I  shall,"  said  Rollo :  "  you  see  the 
parachute  is  expanded,  and  so  brings  down  a 
great  deal  of  air  with  it,  and  this  makes  it 
come  very  slowly.  Air  is  a  real  thing, 
James,  and  it  keeps  the  parachute  back  a 
great  deal." 

So  Rollo  ran  off  after  the  umbrella,  very 
much  interested  in  proving  to  James,  by 
actual  experiment,  that  the  air  was  a  real 
thing.  When  he  came  with  it,  he  was  him- 


self  inclined  to  make  the  first  experiment 
from  the  low  side  of  the  shed.  He  could 
climb  up,  by  means  of  a  fence  at  the  corner. 
James  advised  him,  however,  to  try  it  first 
from  the  end  of  a  woodpile,  which  was  pretty 
high,  but  yet  not  so  high  as  the  shed.  James 
was  not  quite  sure  that  the  experiment  would 
succeed,  and  he  was  afraid  that  Rollo  might 
get  hurt. 

Rollo  said  that  he  was  not  afraid  to  jump 
off  the  shed.  He  knew  the  parachute  would 
bear  him  up.  He  did  not  believe  but  that  he 
could  jump  off  the  house  with  it ;  and,  at  any 
rate,  he  could  jump  off  the  shed,  he  knew. 
He  accordingly  clambered  up,  and,  taking  his 
station  upon  the  eaves,  he  spread  the  um- 
brella over  his  head,  and  then  jumped  off. 

Down  he  came  with  great  violence ;  his 
cap  flew  off  in  one  direction,  and  his  um- 
brella rolled  away  in  another,  as  he  had  to 
put  out  both  his  hands,  to  save  himself,  when 
he  reached  the  ground.  As  it  was,  he  came 
down  upon  all  fours,  and  in  such  a  way,  that 
James  and  Nathan  both  ran  towards  him, 
thinking  that  he  must  be  hurt. 

"  Did  you  hurt  yourself,  Rollo  ? "  said 
James. 

4 


38  AIR. 

"N>,"  said  Hollo,  "not  much." 

"I  don't  think  the  umbrella  did  you  much 
good." 

"No,"  said  Hollo,  as  he  got  up  rubbing 
his  elbows,  "  it  didn't,  and  I  don't  see  what 
the  reason  is." 

"You  came  down  just  as  hard  as  you 
would  without  it." 

"  Yes,"  said  Nathan,  "  and  he  almost  broke 
his  back;  I  don't  believe  the  air  is  any  real 
thing  at  all." 

The  fact  was,  that  the  umbrella  did  do 
some  good.  Rollo  did  not  come  down  quite 
so  hard  as  he  would  have  done  without  it. 
It  retarded  his  descent  a  little.  But  it  was 
not  large  enough  to  enable  him  to  descend 
in  safety.  When  his  father  said  that  a 
parachute  was  in  fact  only  a  large  umbrella, 
he  meant  a  great  deal  larger  than  Rollo  had 
supposed.  A  parachute,  such  as  is  used  with 
balloons,  is  a  great  deal  larger  than  any 
umbrella  that  ever  was  made. 


Q,U  E  S  T  I  O  N  S. 

What  was  Nathan's  wish,  after  he  had  read  his  father 
something  out  of  his  book  I     Did   he  think  that  he  coulif 


39 


fly  if  he  had  wings  ?  Did  his  father  think  so  ?  What  de- 
faiency  did  his  father  think  was  even  more  important  than 
that  of.wings  ?  Did  Nathan  think  that  a  boy  was  stronger 
than  a  bird  ?  Is  a  boy  absolutely  stronger  than  a  bird  ?  Is 
he  relatively  stronger'  What  is  the  meaning  of  relatively 
stronger  ?  Would  a  man  be  strong  enough  to  work  wings 
that  were  sufficiently  large  to  bear  him  up  into  the  air  ? 
Would  there  be  any  great  difficulty  in  constructing  wings 
for  him  if  he  were  strong  enough } 

Is  any  visible  substance  lighter  than  air  ?  What  would 
be  the  consequence  if  any  of  the  loose  substances  about  the 
earth's  surface  were  light  enough  ?  What  are  clouds  com- 
posed of?  What  difficulty  did  Hollo's  father  point  out,  in 
regard  to  their  floating  in  the  air  ?  What  is  a  parachute  9 
Describe  Hollo's  experiment  with  the  umbrella. 


40 


CHAPTER    111. 

VALVE   MAKING. 

ONE  morning,  when  Rollo  awaked,  he 
heard  a  sharp  clicking  against  the  window. 

"Nathan,"  said  he,  "Nathan,  I  believe 
there  is  a  snow-storm." 

But  Nathan  was  too  sleepy  to  hear  or 
understand. 

Rollo  looked  up,  but  there  was  a  curtain 
against  the  window,  and  he  could  not  see 
very  well.  He  listened.  He  heard  a  low, 
moaning  sound  made  by  the  wind,  and  a 
continuance  of  the  sharp  clicking  which  he 
had  heard  at  first. 

When  he  had  got  up,  and  dressed  himself, 
he  found  that  there  was  a  violent  snow-storm. 
At  first  he  was  glad  of  it,  for  he  liked  snow- 
storms. But  then,  pretty  soon,  he  was  sorry, 
for  it  had  been  winter  a  long  time,  and  he 
was  impatient  for  the  spring. 

After  breakfast,  he  and  Nathan  read  and 
studied  for  two  hours,  under  their  mother's 


VALVE    MAKING.  41 

direction.  When  they  were  released  from 
these  duties,  Rollo  proposed  to  Nathan  that 
they  should  go  out  into  the  shed,  and  see 
how  the  storm  came  on.  There  was  a  large 
door  in  the  shed,  opening  towards  the  street, 
where  they  could  stand,  protected  from  the 
wind,  and  see  the  drifts  of  snow. 

They  accordingly  put  on  their  caps,  and 
went.  They  found  that  the  snow  was  pretty 
deep.  It  was  heaped  up  upon  the  fence 
and  against  the  windows ;  and  there  was  a 
curious-shaped  drift,  with  the  top  curled 
over  in  a  singular  manner,  running  along 
from  the  corner  of  the  shed  towards  the 
garden  gate. 

"  Ah,"  says  Rollo,  "  when  it  clears  up,  I 
mean  to  go  and  wade  through  it." 
.  "  And  I  too,"  said  Nathan. 

"  O  Nathan,"  said  Rollo,  "  it  is  over  your 
head." 

"Hark!"  said  Nathan;  "who  is  that 
pounding  in  the  barn?  " 

"  It  is  Jonas,  I  suppose,"  said  Rollo.  "  I 
mean  to  go  out  and  see  what  he  is  doing." 

"  How  are  you  going  to  get  there  ?  "  said 
Nathan. 

b*  4* 


42 


"  O,  I  can  put  on  my  boots,"  said  Hollo, 
''  and  go  right  out  through  the  snow." 

"  I  wish  I  could  go,"  said  Nathan. 

"  Well,"  said  Rollo,  "  I  can  carry  you  on 
my  back." 

Nathan  clapped  his  hands  at  this  proposal, 
being  doubly  pleased  at  the  prospect  of  both 
getting  into  the  bam  to  see  what  Jonas  was 
doing,  and  also  ~»f  having  a  ride,  on  the  way. 

So  Rollo  put  on  his  boots,  while  Nathan 
went  and  got  Rollo  his  straps,  to  fasten  his 
pantaloons  around  them.  When  all  was 
ready,  Rollo  sat  down  upon  the  step  of  the 
door,  in  order  that  Nathan  might  get  on 
easily. 

"  We'll  play  that  I  am  a  camel,"  said 
Rollo,  "  and  that  I'm  kneeling  down  for  you 
to  get  on." 

"Do  camels  kneel  down,"  said  Nathan, 
"  when  the  men  want  to  ride  ?  " 

"  Yes,"  said  Rollo  ;  and  so  saying,  he  rose 
laboriously,  with  his  heavy  burden  upon  his 
shoulders.  He  staggered  along  with  some 
difficulty,  but  yet  safely,  until  he  came  to 
the  great  drift ;  and,  after  wallowing  into  the 
midst  of  it,  he  lost  his  balance,  and  both 


VALVE    MAKING.  i 

camel  and  driver  rolled  over  together  mto 
the  snow.  The  snow  got  up  under  Natnan's 
sleeve,  and  he  began  to  cry. 

"O  Nathan,"  said  Rollo,  "don't  cry.  I'll 
run  and  get  Jonas  to  come  and  carry  you  in." 

So  Rollo  ran  into  the  barn,  and  called  to 
Fonas  to  come  quick.  Jonas  laid  down  his 
hammer  upon  the  bench,  and  followed  Rollo. 
He  found  Nathan  in  the  snow,  and  took  him 
up  in  his  arms,  and  carried  him  into  the 
barn. 

As  soon  as  he  got  him  under  cover,  he 
brushed  the  snow  off,  and  told  him  not  to 
cry.  "  I've  got  a  fire  in  the  shop,"  said  he, 
"  and  you  shall  see  me  do  my  work.  I'm 
mending  the  bellows." 

So  he  led  Nathan  through  the  barn,  and 
thence  along  under  a  shed  to  a  sort  of  shop- 
room,  where  there  was  a  large  fireplace  and 
a  fire.  Rollo  put  on  some  sticks,  which 
made  a  great  blaze  ;  and  so  Nathan  soon  got 
warm  and  dry,  and  forgot  all  his  troubles. 
Then  Jonas  sat  him  up,  upon  a  high  stool, 
near  the  bench,  where  he  could  see  him  work. 
He  was  just  drawing  out  some  of  the  nails, 
by  which  the  leatfier  of  the  bellows  was 
nailed  to  the  sides. 


••What  is  the  matter  with  the  bellows?*1 
said  Nathan. 

"  The  valve  is  out  of  order,"  replied  Jonas. 

"  The  valve,"  repeated  Nathan  ;  "  what  is 
the  valve  ? " 

"  The  valve  is  a  kind  of  clapper,"  said 
Jonas.  "  I  will  show  it  to  you  in  a  few 
minutes." 

So  Jonas  proceeded  to  take  off  the  leather 
from  one  of  the  sides  of  the  bellows.  There 
was  a  hole  in  one  of  the  sides,  but  no  hole 
in  the  other.  Nathan  "had  often  noticed  the 
hole,  but  he  did  not  know  what  it  was  for. 

"  What  is  the  hole  for  ?  "  said  Nathan. 

"  That  is  to  let  the  air  in,"  said  Jonas. 

"What  do  they  want  the  air  to  come  in 
for? "  said  Nathan. 

"To  make  wind  of,"  said  Jonas. 

"  Do  they  make  wind  out  of  air  ? "  said 
Nathan. 

"  Yes,"  said  Jonas,  "  they  get  the  bellows 
full  of  air,  and  then  blow  it  out  through  the 
nose,  and  that  makes  wind." 

"  Wind  is  air,  put  in  motion,"  said  Rollo. 
'•'  I  read  it  in  a  book." 

:i  By  this  time,  Jonas  had  taken  off  the 
leather  so  far  that  Nathan  could  see  into 


VALVE    MAKING.  45 

the  bellows.  He  saw  that  there  was  a  little 
clapper  over  the  hole,  in  one  of  the  sides  of 
the  bellows. 

"  Is  that  the  valve  ? "  said  he  to  Jonas. 

•'<  Yes,"  said  Jonas. 

"  What  is  it  for  ?  "  said  Nathan. 

"It  is  to  keep  the  wind  from  coming  out 
of  that  hole." 

"  Why  don't  they  want  the  wind  to  go 
out  of  that  hole  ?  "  said  Nathan. 

"  Because,"  said  Jonas,  "  they  want  it  to 
go  to  the  fire,  —  to  blow  the  fire." 

"  You  see,"  said  Hollo,  "  it  can't  go  out 
of  the  hole,  and  so  it  has  to  go  out  of  the 
long  nose,  which  is  pointed  towards  the 
fire." 

"What  makes  it  go  out  at  all?"  said 
Nathan. 

"  Why,  when  we  blow  the  bellows,  we 
press  the  two  sides  together,  and  that  presses 
the  wind  out.  It  can't  go  out  of  the  hole 
whence  it  came  in,  because  the  clapper  stops 
it  up,  and  so  it  goes  out  the  long  nose,  right 
into  the  fire,  and  makes  the  fire  burn." 

By  this  time,  Jonas  had  got  the  leather  off 
so  far,  that  he  could  get  at  the  clapper  to 
mend  it.  He  told  the  boys  that  it  was 


46  AIR. 

old  and  worn  out,  and  he  must  make  a 
new  one. 

"  How  are  you  going  to  make  it  ?  "  said 
Hollo. 

"  You'll  see,"  said  Jonas,  "  if  you  watch 
me  closely." 

So  Jonas  took  some  leather,  and  cut  out  a 
piece,  of  an  oblong  shape,  a  little  wider  than 
the  hole,  and  about  twice  as  long.  Then  he 
laid  this  down  over  the  hole.  It  covered  it 
entirely.  Then  he  took  some  small  carpet 
nails,  and  nailed  one  of  the  ends  of  the 
leather  down  to  the  board.  Then  Jonas  put 
his  hand  down  under  the  board,  and  run  one 
of  his  fingers  up  through  the  hole,  and  pushed 
the  leather  up  a  little  way. 

"  There,"  said  he  to  the  boys,  "  you  see 
I  have  nailed  the  leather,  so  that,  when  it 
lies  down  in  its  place,  it  covers  the  hole  com- 
pletely ;  and  yet  I  can  push  it  up  a  little  with 
my  fingers,  so  that  there  will  be  an  opening." 

Then  Jonas  cut  a  small  leather  strap,  and 
nailed  one  end  of  it  down  upon  one  side  of 
the  clapper,  and  the  other  end  upon  the 
other  side  of  the  clapper.  He  put  one  little 
carpet  nail  into  each  end  of  the  strap.  The 
strap,  when  it  was  nailed,  passed  directly 


VALVE    MAKING.  4? 

across  the  clapper  or  valve.  It  was  not 
drawn  tight  across,  but  it  lay  upon  the  clap- 
per loosely.  The  ends  were  nailed  tight, 
but  the  middle  rested  loosely  upon  the 
clapper. 

"  Now,"  said  Jonas,  "  I  can  push  the 
clapper  up  a  little  way,  but  I  can't  push  it 
far.  The  strap  keeps  it  from  coming  up 
far." 

"  But  why,"  said  Nathan,  "  do  you  want 
it  to  go  up  at  all  ?  " 

"  To  let  the  air  in,"  said  Jonas.  "  When 
I  get  the  leather  all  nailed  on  again,  I'll  show 
you  the  whole  operation  of  it." 

"  And  you  can  be  telling  us  about  it  in  the 
mean  time,"  said  Hollo. 

"Well,  then,"  said  Jonas-,  "when  I  lift  up 
the  upper  side  of  the  bellows  by  the  handle, 
to  blow,  the  air  comes  in  by  the  hole.  The 
clapper  lifts  up  a  little  way,  and  lets  it  in. 
Then,  when  I  press  down  the  handle  again, 
it  presses  the  air  out  through  the  nose,  be- 
cause it  can't  go  back  through  the  valve 
hole." 

"  Why  not  ?  "  said  Nathan. 

"Because,"  said  Jonas,  "the  valve  falls 
down  over  the  hole,  and  stops  it  up.  It  is 


48 


made  so  as  to  lift  up  easily,  and  then  to  fall 
down  and  cover  the  hole  exactly,  and  prevent 
the  air  going  out  the  same  way  it  came  in. 
So,  as  it  cannot  get  out  by  the  valve,  it  has 
all  to  go  out  through  the  nose.  If  the  nose 
were  stopped  up,  it  could  not  get  out 
at  all." 

"  And  what  then  ?  "  said  Rollo. 

"  Why,  then,"  replied  Jonas,  "  you  could 
not  bring  the  two  sides  of  the  bellows  together 
again.  The  air  between  would  keep  them 
apart." 

"  I  should  like  to  try,"  said  Rollo. 

"  Well,"  said  Jonas  ;  "  and  there  are  some 
other  experiments  you  may  perform  with  it 
too." 

At  length,  Jonas  said  ihat  he  had  got  the 
leather  all  nailed  on,  and  they  might  try  the 
experiment.  He  took  hold  of  the  nose  of  the 
bellows,  and  held  his  thumb  near  the  end  of 
it,  ready  to  stop  up  the  hole. 

"  Now,  Nathan,  you  may  take  hold  of  the 
handles,  and  pull  them  apart  as  if  you  were 
going  to  blow." 

Nathan  did  so.  He  pulled  the  handles 
apart,  and  held  them  open. 

"  Now,"  said  Jonas,  "  I  will  stop  up  the 


VALVE    MAKING.  49 

nose,  and  the  valve  will  close  itself;  and  then 
you  will  find  that  you  cannot  bring  the  sides 
together  again." 

So  Jonas  put  his  thumb  over  the  hole,  and 
told  Nathan  to  blow. 

Nathan  pressed  hard,  and  the  sides  came 
together  again,  about  as  easily  as  usual. 

"  What !  "  exclaimed  Jonas  with  surprise. 
He  did  not  know  what  to  make  of  the  failure 
of  his  experiment. 

"  There  must  be  a  leak  somewhere,"  said 
he.  And  he  took  the  bellows  out  of  Nathan's 
hand  to  look  for  it. 

He  found  there  was  a  corner,  on  the  side 
opposite  to  the  one  where  he  had  been  work- 
ing, where  the  leather  was  open,  he  having 
forgotten  to  nail  it  down. 

"  Ah !  "  said  he,  "  here  is  the  difficulty 
When  I  have  nailed  this  down,  we  will  try 
again." 

"  Is  that  a  leak  ?  "  said  Nathan. 

"Yes,"  said  Jonas.  "When  you  worked 
the  bellows,  you  pressed  the  air  all  out 
through  there.  I  did  not  know  that  that 
was  open.  Let  me  nail  this  down,  and  then 
we  will  begin  our  experiment  regularly." 
c  5 


50 


QUESTIONS. 


What  was  Jonas  doing  in  the  shop,  when  Rollo  and 
Nathan  went  out  to  find  him  ?  What  part  of  the  bellows 
was  out  of  order  ?  How  did  he  make  a  new  valve  ?  How 
did  he  fasten  it  to  its  place  ?  Did  he  nail  down  only  one 
edge,  or  both  edges  ?  Why  did  he  want  the  other  edge  to 
be  left  at  liberty  ?  How  did  he  prevent  its  lifting  up  too 
far  ?  What  was  the  first  experiment  which  he  performed 
with  the  bellows,  after  he  had  finished  the  mending?  Did 
it  succeed  at  first  ?  Why  not  ?  In  working  a  pair  of  bel- 
lows, where  does  the  air  come  in  ?  Where  does  it  go  out  ? 
Why  cannot  the  air  escape  through  the  valve  where  it 
comes  inf 


51 


CHAPTER    IV. 

EXPERIMENTS. 

WHEN  Jonas  had  finished  nailing  down 
the  corner,  he  said,  "  Now  there  are  several 
experiments,  which  we  can  perform  with  the 
bellows.  I  will  be  the  professor,  and  you 
two  shall  be  my  class  in  philosophy,  and  I 
will  direct  you  how  to  make  the  experi- 
ments. 

"  First,"  said  Jonas,  "  you,  Rollo,  may 
take  hold  of  the  nose  of  the  bellows  with 
your  hand,  in  such  a  way  as  to  put  your 
thumb  over  the  end  of  it,  to  stop  it  up,  and 
then  let  Nathan  try  to  blow." 

Rollo  did  so,  and  Nathan  tried  to  blow. 
He  found  that  he  could  open  the  bellows 
very  easily ;  but  when  he  attempted  to  press 
the  sides  together  again,  he  could  riot.  lie 
crowded  the  handle  belonging  to  the  upper 
side  down,  as  hard  as  he  could,  but  it  would 
not  move. 

"  What  makes  it  do  so? "  said  Nathan. 


52 


"  The  air  inside,"  said  Jonas.  "  We  have 
stopped  up  all  the  places,  where  it  could  get 
out.  The  valve  stops  itself.  Rollo  stops  the 
nose  with  his  thumb,  and  I  have  nailed  the 
leather  down  close,  about  all  the  sides.  And 
so  the  air  can't  get  out,  and  that  keeps  you 
from  bringing  the  sides  together  again." 

Nathan  tried  again  with  all  his  strength. 
The  sides  came  togethei  very  slowly. 

"  They're  coming,"  said  he. 

"  Yes,"  said  Jonas.  "  They  come  a  little, 
just  as  fast  as  the  air  can  leak  out  through 
the  little  leaks  all  around." 

"  I  thought  you  stopped  all  the  leaks," 
said  Nathan. 

"  Yes,"  replied  Jonas,  "  I  stopped  all  the  real 
leaks,  but  still  I  can't  make  it  perfectly  tight. 
Some  air  can  escape  between  the  leather  and 
the  nails  all  around,  and  just  as  fast  as  it  can 
get  out,  so  fast  you  can  press  the  sides  to- 
gether, and  no  faster." 

Here  Nathan  tried  again  with  all  his 
strength ;  but  he  could  only  bring  the  sides 
together  very  slowly. 

"  Now  comes  the  second  experiment,"  said 
Jonas.  "  While  Nathan  is  trying  to  press 
the  two  handles  together,  you,  Rollo,  may 


EXPERIMENTS.  53 

run  your  finger  into  the  hole,  and  push  up 
the  valve  a  little." 

Rollo  did  so.  He  pushed  up  the  valve  a 
little  with  his  finger,  and  that  allowed  the 
air  to  escape  through  the  opening.  The 
consequence  was,  that  the  bellows  collapsed 
at  once  under  the  pressure  which  Nathan 
was  exerting  upon  them. 

"  There,"  said  Jonas,  "  you  see  that  when 
the  air  is  kept  in,  you  cannot  bring  the  sides 
together;  but  when  I  let  the  air  out,  then 
they  come  together  easily." 

"  Yes,"  said  Nathan ;  "  do  it  again, 
Rollo." 

So  they  performed  the  experiment  again. 
Nathan  pulled  the  handles  apart  wide,  while 
Rollo  kept  his  thumb  over  the  nose,  to  keep 
the  air  from  issuing  through.  Then  Nathan 
tried  to  press  them  together  ;  but  he  could  not, 
until  Rollo  put  his  finger  under,  and  pushed 
up  the  valve  a  little,  and  then  they  came 
together  again  very  easily. 

"  The  air  is  a  real  thing,  I  verily  believe," 
said  Nathan. 

"Yes,"  said  Rollo,  "I  know  it  is.  And 
now  for  the  third  experiment,  Jonas." 

"The  third  experiment,"  said  Jonas,  "is 
5* 


54 


this.  Turn  the  bellows  bottom  upwards, 
and  try  to  blow." 

Nathan  did  so.  He  found  that  he  could 
work  the  bellows  easily  —  too  easily,  in  fact ; 
but  they  did  not  blow. 

"  Hold  your  hand  opposite  the  nose,  and 
see  if  any  wind  comes,"  said  Jonas. 

They  did  so  ;  there  was  no  wind,  or  rather 
scarcely  any. 

"  The  reason  is,"  said  Jonas,  "  that,  when 
the  bellows  are  bottom  upwards,  the  valve 
hangs  down  off  from  the  hole  all  the  time, 
and  lets  the  air  all  out  through  the  hole  in 
the  side ;  and  it  can  come  out  more  easily 
there  than  through  the  nose,  and  so  it  don't 
blow  well." 

"  Well,  Jonas,"  said  Hollo,  "  that's  a  pretty 
good  experiment ;  but  what  is  the  next  ?  Let 
me  try  the  next.  Nathan,  it  is  my  turn." 

"  The  next  experiment,  which  is  the 
fifth, " 

"No,  the  fourth."  said  Nathan. 

"The  fourth,  then,"  said  Jonas,  "is  tc 
prove  what  I  said  to  you  —  that  the  air,  which 
is  blown  out  at  the  nose  of  the  bellows,  really 
comes  in  through  the  valve.  Let  me  see,  — 
I  want  something  to  make  a  smoke." 


EXPERIMENTS.  55 

•'  Will  not  paper  do  ? "  said  Rollo. 

"  Yes,"  said  Jonas,  "  here  is  some  brown 
paper,  which  will  do."  So  Jonas  rolled  it  up, 
and  told  Rollo  to  set  it  on  fire,  and  then,  when 
it  was  well  burning,  to  step  on  it  with  his 
foot,  and  put  the  flame  out. 

Rollo  did  so,  and  the  paper  lay  in  a  heap, 
making  a  great  smoke  upon  the  hearth,  just 
before  the  fire. 

"  Now,"  said  Jonas,  "  put  the  bellows  upon 
its  edge,  by  the  side  of  the  paper,  so  as  to 
have  the  valve  near  the  smoke,  and  then 
hold  still  a  minute,  until  the  smoke  comes 
up  steadily  by  the  valve." 

When  this  was  done,  Jonas  told  Nathan 
to  take  hold  of  the  nose  of  the  bellows,  to 
steady  it,  so  that  Rollo  could  blow.  He  then 
directed  Rollo  to  lean  the  bellows  over  a  little 
towards  the  smoke,  so  that  the  moving  side 
should  not  rub  upon  the  hearth,  when  he 
began  to  blow. 

"  Now,"  he  continued,  "  if  you  work  the 
bellows,  you  will  see  that  the  smoke  will  be 
drawn  in  through  the  valve,  and  then  will 
come  out  through  the  nose." 

This  experiment  succeeded  perfectly  well, 
only  just  hi  the  midst  of  the  interest  that 


56 


they  felt,  in  seeing  the  smoke  come  pouring 
out  through  the  nose,  they  heard  a  bell  ring 
at  the  house.  They  knew  at  once  that  this 
bell  was  for  Rollo  and  Nathan ;  and  so  the 
two  boys  jumped  up  from  the  hearth,  and  ran 
out  to  see  what  was  wanted.  They  went 
through  the  shed  into  the  barn,  and  thence 
on  till  they  came  to  the  great  bam  door, 
where  they  had  come  in.  There  Rollo 
stopped,  —  for  he  did  not  like  to  go  out  into 
the  snow, — and  asked  Dorothy,  who  was 
ringing  the  bell,  what  she  wanted. 

"  Where's  Nathan  ?  "  said  Dorothy. 

"  He's  here  with  me,"  said  Rollo.  Nathan 
was  coming  along,  as  fast  as  he  could,  through 
the  barn. 

"  Do  you  want  us  ?  "  said  Rollo. 

"No,"  said  Dorothy,  " only  we  did  not 
know  where  you  were.  You  may  stay  half 
an  hour  more,  and  then  it  will  be  nearly 
dinner  time." 

Dorothy  then  went  in,  leaving  the  boys  at 
the  great  barn  door.  The  door  opened  in 
such  a  direction,  that  the  wind  did  not  blow 
in;  arid  Rollo  and  Nathan  looked  out  for 
some  time,  watching  the  falling  snow,  and 
listening  to  the  wind,  as  it  roared  through 


EXPERIMENTS.  Hi 

the  tops  of  the  trees.  At  last,  when  they 
began  to  think  of  returning  to  the  shop. 
Hollo  said,  — 

"  O  Nathan,  let  us  go  and  hide,  and  then 
Jonas  will  not  know  where  we  are." 

"Well,"  said  Nathan,  "we  will." 

The  boys  accordingly  began  to  look  about 
the  barn  for  a  place  to  hide.  It  was  a  large 
barn,  with  stalls  for  oxen  and  cows,  and  cribs 
for  horses,  and  one  or  two  calf-pens.  Then 
there  was  a  granary  in  one  corner,  and  a  tool- 
room near  it,  and  lofts  and  scaffolds  above. 
The  boys  found  plenty  of  places  to  hide  in, 
and  it  took  them  some  time  to  decide  which 
to  choose.  At  last,  they  found  a  good  warm 
place,  by  some  bundles  of  wheat  straw, 
up  in  tlie  barn  chamber ;  and  they  amused 
themselves  by  choosing  out  large  straws,  and 
making  tubes  of  them  to  blow  through 
They  called  them  their  bellows. 

They  entirely  forgot  that  they  were  hid 
from  Jonas,  for  nearly  half  an  hour ;  and  then 
Rollo  proposed  that  they  should  creep  softly 
down,  and  see  what  Jonas  Avas  about.  So 
they  went  down  stairs  on  tiptoe  ;  Rollo  first, 
and  Nathan  following.  They  crept  softly 
along  to  the  door  leading  out  into  the  shed, 


58 


through  which  they  had  to  pass  in  order  to 
get  to  the  shop ;  and  Rollo  was  going  to  open 
this  softly,  when,  to  his  surprise,  he  found  it 
fastened. 

"Why,  Nathan,"  said  he,  "this  door  is 
fastened." 

"How  came  it  fastened ?  "  said  Nathan. 

"  I  don't  know,"  said  Rollo,  "  unless  Jonas 
fastened  it.  I  think  he  must  have  finished 
his  work,  and  gone  into  the  house  ;  and  so 
he  has  fastened  this  door." 

"  And  now  he  won't  come  and  find  us," 
said  Nathan. 

"  No,"  said  Rollo,  "  and  we  must  go  out 
the  front  door.  And  I  don't  care  much,"  he 
continued,  "for  it  is  pretty  near  dinner  time." 

The  boys  then  went  back  to  the  front  door 
of  the  barn,  and,  to  their  surprise  and  alarm, 
found  that  fastened  too. 

"  What  shall  we  do  ?  "  said  Rollo  ;  "  Jonas 
has  fastened  us  in."  As  Rollo  said  this,  his 
face  assumed  an  expression  of  great  solicitude, 
and  Nathan  began  to  cry. 

"  Don't  cry,  Nathan,"  said  he  ;  "  we  can 
find  some  way  to  get  out.  But  I  don't  see, 
I  confess,  what  made  Jonas  lock  us  in." 

The  truth  was,  that  Jonas  did  not  know 


EXPERIMENTS.  59 

-hat  the  boys  were  in  the  barn  when  he 
fastened  it  up.  As  they  did  not  come  back 
after  they  had  gone  to  answer  the  bell,  he 
supposed  that  they  had  gone  into  the  house ; 
and  when  he  was  ready  to  come  in  himself, 
lie  shut  and  fastened  the  back  doors  of  the 
barn,  as  he  usually  did  when  he  left  the  shop. 
He  then  came  around  to  the  front  barn  door, 
and  although  that  was  on  the  sheltered  side, 
so  that  the  wind  did  not  blow  in,  he  thought 
it  possible  that  the  wind  might  change,  and  so 
drive  the  snow  in  upon  the  barn  floor ;  and 
therefore,  to  make  all  safe,  he  thought  that 
he  would  shut  them,  too.  He  accordingly 
shut  the  great  doors,  and  put  the  fid  into  the 
staple.  The  fid  is  a  wooden  pin,  to  be  passed 
through  the  staple  when  the  doors  are  shut, 
to  fasten  them.  The  doors  cannot  be  opened 
again  until  the  fid  is  taken  out. 

Rollo  went  all  around  the  barn,  trying  to 
find  some  place  where  he  could  get  out ;  but 
he  could  not  find  any  place  at  all. 

uLet  us  go  up  stairs,"  said  he,  at  length, 
to  Nathan. 

"O,  it  will  not  do  any  good  to  go  up 
stairs,"  said  Nathan.  "  It  would  kill  us  to 
jump  out  the  window." 


60 


"  I  know  we  can't  jump  out  the  window," 
said  Rollo,  "  but  perhaps  we  can  find  out 
some  way  to  get  down.  O,  there  is  a  ladder  ; 
I  remember  now,  Nathan,  there  is  a  ladder. 
We  can  get  down  from  the  window  by  the 
ladder." 

"  I  shall  be  afraid  to  go  down  the  ladder," 
said  Nathan. 

"  O  no,"  said  Rollo,  "  I  will  go  first,  and 
see  if  it  is  safe." 

By  this  time  they  had  reached  the  barn 
chamber.  There  was  a  window  in  it,  with 
glass,  over  the  great  barn  door ;  but  Rollo 
could  not  get  it  open.  He  told  Nathan  that, 
if  he  could  only  get  it  open,  and  could  find 
a  long  pole,  he  could  reach  it  down,  and 
knock  the  fid  out,  and  so  open  the  great 
doors.  But,  with  all  his  efforts,  he  could  not 
raise  the  window. 

There  \vas  another  window,  which  had  no 
glass,  but  was  closed  by  a  wooden  shutter, 
which  opened  upon  hinges  like  a  door. 
Rollo  said  he  meant  to  open  this  window. 
Now,  it  happened  that  this  window  was^ipon 
that,  side  of  the  barn  which  was  exposed  to 
the  wind  and  storm ;  and,  the  moment  that 
Rollo  had  pushed  open  the  shutter  a  little 


EXPERIMENTS.  61 

way,  the  wind  forced  it  instantly  from  his 
hand,  and  slammed  it  back  against  the  side 
of  the  barn,  with  great  violence.  It  almost 
pulled  Rollo  himself  out  of  the  window. 

Nathan  looked  frightened.  Rollo  himself 
looked  somewhat  astonished  at  such  an  un- 
expected effect ;  but  presently  said,  — 

"  Well,  Nathan,  I  rather  think  that,  if  you 
had  had  hold  of  that  shutter,  you  would 
have  thought  that  air  was  a  real  thing." 

"  O,  that  was  the  wind,  Rollo ;  that  was 
the  wind"  said  Nathan. 

Rollo  did  not  answer,  but  went  to  the 
ladder,  which  was  standing  up  against  the 
hay-loft.  It  was  a  pretty  long,  but  yet  a 
very  light  ladder;  and  Rollo  and  Nathan 
succeeded,  after  some  difficulty,  in  getting  it 
down,  and  in  running  the  end  out  of  the 
window.  When  the  lower  end  reached  the 
ground,  the  upper  end  was  two  or  three  feet 
above  the  bottom  of  the  window ;  so  that 
Rollo  could  easily  get  upon  it  to  descend. 
The  wind  and  storm,  which  raged  Avith 
great  violence,  were  somewhat  terrifying ; 
but  he  knew  that  the  ladder  was  secure,  the 
upper  part  being  confined  in  the  window ; 
and  so  he  resolutely  descended.  When  ho 


62  AIR. 

had  fairly  reached  the  ground,  he  looked  up, 
with  an  expression  of  great  satisfaction  upon 
his  countenance,  and  said,  — 

"  There  !  now,  Nathan,  for  your  turn." 

But  Nathan  was  afraid  to  venture ;  and 
Rollo  himself  was  half  afraid  to  have  him 
make  the  attempt.  While  they  were  stand- 
ing in  this  perplexity,  Rollo  heard  a  voice 
behind  him,  calling  out, — 

"  Rollo." 

Rollo  turned,  and  saw  Dorothy  standing 
by  the  door. 

"  What  are  you  doing,  Rollo  ? "  said 
Dorothy. 

"  I  am  trying  to  get  Nathan  out  of  the 
barn,"  said  Rollo. 

"  How  came  he  in  the  barn  ? "  said 
Dorothy. 

"  Why,  Jonas  locked  us  in,  and  I  had  to 
come  down  the  ladder ;  but  Nathan  is  afraid, 
and  I  can't  get  him  out." 

"  Why  don't  you  go  to  the  door,  and  let 
him  right  out  ?  " 

"O,"  said  Rollo,  laughing,  "I  never 
thought  of  that.  Go  down,  Nathan,"  he 
continued,  "  to  the  door,  and  I  will  go  round 
and  knock  out  the  fid." 


EXPERIMENTS.  63 

So  Nathan  went  down,  and  Hollo,  meeting 
him  there,  knocked  out  the  fid,  and  released 
him  from  his  imprisonment. 


QUESTIONS. 

What  was  the  first  experiment  with  the  bellows,  de- 
scribed in  this  chapter  ?  Why  could  not  Nathan  press  the 
two  sides  of  the  bellows  together,  while  the  nose  was 
stopped  ?  What  was  the  second  experiment  ?  What  was 
the  effect  produced  by  turning  the  bellows  bottom  upwards, 
as  in  the  third  experiment  ?  What  was  the  fourth  experi- 
ment ?  What  was  the  use  of  the  smoke  of  the  paper  1 
How  were  the  experiments  interrupted  ?  What  evidence 
did  Rollo  and  Nathan  have  that  the  air  waa  a  real  sub- 
stance, when  in  the  barn  chamber  ? 


64 


CHAPTER    V. 

PRESSURE. 

ONE  evening,  just  after  tea,  Rollo  came  to 
his  father,  who  was  sitting  by  the  side  of  the 
fire,  and  said,  — 

"  Father,  I  wish  we  could  see  the  air,  as 
we  can  the  water,  and  then  perhaps  we  could 
try  experiments  with  it." 

"  O,  we  can  try  experiments  with  the  air 
as  it  is,"  said  his  father. 

"Can  we?"  said  Rollo;  "I  don't  see 
how." 

"  We  cannot  see  the  air,  it  is  true  j  but 
then  we  can  see  its  eifects,  and  so  we  can 
experiment  upon  it." 

-  Well,  at  any  rate,"  said  Rollo,  "  we 
can't  build  a  dam,  and  make  it  spout  through 
a  hole,  like  water." 

.  "  No,"  said  his  father,  "  not  exactly.  In 
your  dam,  for  instance,  when  it  was  full,  you 
had  water  on  one  side  of  the  board,  and  no 
water  on  the  other  ;  and  then,  by  opening  a 


PRESSURE.  65 

hole  in  the  board,  the  water  spouted  through  j 
but  we  cannot  very  well  get  air  on  one  side 
of  a  partition,  and  no  air  on  the  other  ;  if  we 
could,  it  would  spout  through  very  much  as 
the  water  did." 

"  Why  can't  we  do  thab>  sir  ?  "  said  Hollo. 

"  Because,"  replied  his  father,  "  we  are  all 
surrounded  and  enveloped  with  air.  It 
spreads  in  every  direction  all  around  us,  and 
rises  many  miles  above  us.  Whereas,  in 
respect  to  water,  you  had  one  little  stream 
before  you,  which  you  could  manage  just 
as  you  pleased.  If  you  were  down  at  the 
bottom  of  the  sea,  then  the  water  would  be 
all  around  you  and  above  you ;  and  there, 
even  if  you  could  live  there,  you  could  not 
have  a  dam." 

"  No,  sir,"  said  Rollo,  "  the  water  would 
be  everywhere." 

"Yes,"  replied  his  father,  "and  the  air  is 
everywhere.  If,  however,  we  could  get  it 
away  from  any  place,  as,  for  instance,  from 
this  room,  then  bore,  a  hole  through  the  wall, 
the  weight  of  the  air  outside  would  crowd  a 
portion  of  it  through  the  hole,  exactly  as  the 
weight  of  the  water  above  the  board  in  your 
c*  6* 


66  AIR. 

dam  crowded  a  part  through  the  hole  in  the 
board." 

"  I  wish  we  could  try  it,"  said  Rollo. 

"  We  can  try  it,  in  substance,"  said  his 
father,  "  in  tnis  room ;  or  —  no,  the  china 
closet  will  be  better." 

There  was  a  china  closet,  which  had  two 
doors  in  it.  One  door  opened  into  the  par- 
lor, where  Rollo  and  his  father  were  sitting 
The  other  door  opened  into  the  back  part  of 
the  entry.  Rollo 's  father  explained  how  he 
was  going  to  perform  the  experiment,  thus  :  — 

"  If  we  could,  by  any  means,  get  all  the 
air  out  of  the  closet  for  a  moment,  then  the 
pressure  of  the  air  outside  would  force  a  jet 
of  it  in  through  the  key-holes  of  the  doors, 
and  the  crevices." 

"  And  how  can  we  get  the  air  out  ?  "  said 
Rollo. 

"We  "an't,"  said  his  father,  "get  it  all 
out ;  but  we  can  get  a  part  of  it  out  by  shut- 
ting the  door  quick.  The  door  will  carry 
with  it  a  part  of  the  air  that  was  in  the 
closet,  and  then  the  outside  air  will  be 
spouted  in,  through  the  key-hole  of  the 
other  door.  Only  we  can't  see  it,  as  we  can 
the  water." 


PRESSURE.  67 

"  No,"  said  Rollo ;  "  but  I  can  put  my 
hand  there,  and  feel  it." 

"  A  better  way,"  said  his  father,  "  would 
be  to  hold  a  lamp  opposite  to  the  key-hole, 
and  see  if  it  blows  the  flame." 

Rollo  tried  the  experiment,  in  the  way 
his  father  had  described.  He  went  into  the 
closet  with  the  lamp.  He  held  the  lamp 
opposite  to  the  key-hole,  and  pretty  near  to  it, 
and  then  he  asked  Nathan  to  shut  the  other 
door  suddenly.  Nathan,  who  was  standing 
all  ready  by  the  other  door,  which  was 
about  half  open,  put  his  two  hands  against 
it,  and  pushed  it  to,  with  all  his  strength, 
producing  a  great  concussion. 

"  O  Nathan,"  said  his  father,  "  you  need 
not  be  quite  so  violent  as  that." 

"It  succeeded,  father,  it  succeeded,"  said 
Rollo. 

"I'm  glad  it  succeeded,"  said  his  father ; 
"  but  Nathan  need  not  have  shut  the  door 
with  so  much  force." 

"I  wanted  to  drive  out  all  the  air,"  said 
Nathan. 

"  I'll  show  you  how  to  do  it,"  said  his 
father. 

Rollo's  father  accordingly  arose,  and  came 


68 


to  the  closet  door.  He  opened  the  dooi  wide, 
and  then  explained  to  the  boys,  that  the  be- 
ginning of  the  movement  of  the  door,  when 
it  was  wide  open,  did  not  drive  out  any  air. 

"  For,"  said  he,  "  there  is  so  large  a  space 
between  the  edge  of  the  door  and  the  wall, 
that  the  air  that  is  put  in  motion  by  the 
movement  of  the  door,  can  pass  directly 
round  the  edge,  back  into  the  closet  again. 
It  is  only  when  the  door  is  almost  shut, 
when  the  edge  of  it  comes  close  to  the  cas- 
ing all  around,  that  the  movement  of  the 
door  drives  the  air  out." 

Then  he  took  hold  of  the  latch  of  the 
door,  and  put  it  almost  to,  very  gently.  He 
turned  the  latch  so  as  to  prevent  its  snap- 
ping against  the  catch,  and  then  pushed  it 
suddenly  into  its  place  three  or  four  times, 
opening  the  door  only  a  very  little  way 
every  time. 

"Now,"  said  he,  "hold  the  lamp  at  the 
key-hole,  and  watch  the  flame,  while  I  shut 
the  door  two  or  three  times  in  this  way." 

Rollo  did  so,  Nathan  standing  all  the 
time  by  his  side.  They  observed  that  the 
flame  of  the  lamp  was  driven  into  the  room 
every  time  the  door  was  shut ;  proving  that, 


PRESSURE.  69 

every  time  a  little  of  the  air  was  driven  out 
by  the  door,  a  little  puff  rushed  in  at  the 
key-hole. 

"  Let  us  stop  up  the  key-hole,"  said  Rollo, 
"and  then  it  can't  get  in." 

"  Yes,"  said  his  father,  "there  are  a  great 
many  little  crevices  all  around  the  closet, 
where  the  air  can  come  in." 

"  Couldn't  we  stop  those  up  too  ?  "  said 
Rollo. 

"  No,"  said  his  father,  "  not  so  as  to  make 
the  closet  air-tight.  For,  if  the  crevices 
could  all  be  stopped  exactly,  the  air  would 
come  in  through  the  very  wood  itself." 

"  How  ?  "  said  Rollo. 

"  Why,  there  are  little  pores  in  wood,  that 
is,  little  channels  that  the  sap  flowed  in  when 
the  wood  was  growing,  and  the  air  can  pass 
through  these." 

Here  Rollo's  father  observed  that  Rollo 
was  looking  very  intently  at  the  table ;  and 
he  asked  him  what  he  was  doing :  he  said  he 
was  trying  to  find  some  of  the  pores. 

"You  can't  see  them  there."  said  his  fa- 
ther. "St.  Domingo  mahogany  is  a  very 
hard  and  close-grained  kind  of  wood.  If  it 
was  summer,  and  you  could  dig  down  and 


70  AIR. 

get  a  small  piece  of  the  root  of  the  great  elm- 
tree  in  the  yard,  you  could  see  the  pores  and 
channels  there." 

After  some  more  conversation  on  this  sub- 
ject, Hollo  asked  his  father  if  he  could  not 
think  of  some  other  experiments  for  them  to 
try.  His  father  said  that  he  did  not  just  then 
think  of  any  experiment,  but  that,  if  Hollo 
and  Nathan  would  come  and  sit  down  by  the 
fire,  he  would  give  them  some  information 
on  the  subject.  Hollo's  mother  said  that 
she  should  like  to  hear  too.  They  accord- 
ingly waited  until  she  was  ready,  and  then, 
when  all  were  seated,  Mr.  Holiday  began 
thus :  — 

"  Air  is  in  many  respects  much  like  water." 

"Yes,"  interrupted  Rollo,  "just  like  wa- 
ter, only  thinner,  because,  you  see " 

"You  must  not  interrupt  me,"  said  his  fa- 
ther, "  unless  to  ask  some  question,  which  is 
necessary  to  understand  what  I  say.  It  is 
entirely  irregular  for  a  pupil,  instead  of  listen- 
ing to  his  teacher,  to  interrupt,  in  order  to 
tell  something  that  he  knows  himself." 

Rollo's  father  smiled,  as  he  said  this,  but 
Rollo  looked  rather  ashamed.  Then  his  fa- 
ther proceeded :  — 


PRESSURE.  71 

t£  There  is  one  very  remarkable  difference 
between  them.  Water  is  not  compressible 
by  force  ;  but  air  is." 

"  What  is  the  meaning  of  compressible  ?  " 
said  Nathan. 

"  Compressible  things,"  said  his  father,  "are 
those  that  can  be  compressed,  that  is,  pressed 
together,  so  as  to  take  up  less  room  than  they 
did  before.  Sponge  is  compressible.  A  pil- 
low is  compressible.  But  iron  is  not  com- 
pressible, and  water  is  not  compressible." 

"  I  should  think  it  was,"  said  Nathan  ;  "  it 
is  very  soft." 

"  It  is  very  yielding,"  replied  his  father, 
"  when  you  press  it,  but  it  is  not  pressed  into 
any  smaller  space.  It  only  moves  away. 
If  you  have  a  tumbler  half  full  of  water,  and 
press  a  ball  down  into  it,  you  could  not 
crowd  the  water  into  any  smaller  space  than 
it  occupied  at  first ;  but,  as  fast  as  the  ball 
went  down,  the  water  would  come  up  around 
the  sides  of  the  ball." 

"  But  suppose,"  said  Rollo,  "  that  the  ball 
was  just  big  enough  to  fit  the  tumbler  all 
around  ;  then  the  water  could  not  come  up." 

"  And  then,"  said  his  father,  "  you  could 
not  crowd  the  ball  down." 


"  Could  not  a  very  strong  man  ? "  said 
Nathan. 

"  No,"  replied  Iris  father,  "  the  water  can- 
not be  sensibly  compressed.  But  now,  if  the 
tumbler  contained  only  air,  and  if  a  ball  were 
to  be  put  in  at  the  top,  just  large  enough  to 
fit  the  tumbler  exactly,  and  if  a  strong  man 
were  to  crowd  it  down  with  all  his  strength, 
he  would,  perhaps,  compress  the  air  into  half 
the  space  which  it  occupied  before." 

"  Perhaps  the  tumbler  would  break,"  said 
Nathan. 

"  Yes,"  replied  his  father,  "  and  the  tumbler 
will  answer  only  for  a  supposition  ;  but  for  a 
real  experiment  it  would  be  best  to  have  a 
cylinder  of  iron." 

"  What  is  a  cylinder  ?  "  said  Nathan. 

"  An  iron  vessel,  shaped  like  a  tumbler, 
only  as  large  at  the  bottom  as  it  is  at  the  top, 
would  be  a  cylinder.  Now,  if  there  was  a 
cylinder  of  iron,  with  the  inside  turned  per- 
fectly true,  and  a  brass  piston  fitted  to  it " 

,  "  What  is  a  piston  ?  "  said  Nathan. 

"  A  piston,"  said  his  father,  "is  a  sort  of 
stopper,  exactly  fitted  to  the  inside  of  a  cyl- 
inder, so  as  to  slide  up  and  down.  It  is  made 
to  fit  perfectly,  and  then  it  is  oiled,  so  as  to 


PRESSURE.  73 

go  up  and  down  without  much  friction,  that 
is,  hard  rubbing.  There  is  a  sort  of  stem  com- 
ing up  from  the  middle  of  the  piston,  called 
the  piston  rod,  which  is  to  draw  up  the  piston, 
and  to  press  it  down  by. 

"  Now,"  continued  his  father,  "  if  a  strong 
man  had  a  cylinder  like  this,  with  a  piston 
fitted  to  it,  and  a  strong  handle  across  the  top 
of  the  piston  rod,  perhaps  he  might  press  the 
air  into  one  half  the  space  which  it  occupied 
before.  That  is,  if  the  cylinder  was  full  of 
air  when  he  put  the  piston  in,  perhaps  he 
could  get  the  piston  down  half  way  to  the 
bottom.  Then  the  air  would  be  twice  as 
dense  as  it  was  before ;  that  is,  there  would 
be  twice  as  much  of  it  in  the  same  space  as 
there  was  before.  It  would  be  twice  as  com- 
pact and  heavy.  This  is  called  condensing 
air.  The  philosophers  have  ingenious  instru- 
ments for  condensing  air. 

"  If,  however,  a  man  condenses  air  in  this 
way,  by  crowding  down  a  piston,  he  does 
not  begin  the  condensation  when  the  piston 
begins  to  descend.  The  air  is  condensed  a 
great  deal  before  he  begins.  All  the  air 
around  us  is  condensed." 

"  How  comes  it  condensed  ?  "  said  Hollo. 
.d  7 


74  AIR. 

"  Why,  you  recollect  that,  when  you  bored 
a  hole  through  the  board  in  the  bottom  of  your 
dam,  the  water  spouted  out." 

"  No,  father,"  said  Rollo,  "  we  pulled  the 
plug  out ;  Jonas  bored  the  hole." 

"  Well,"  said  his  father,  "  the  water  spout- 
ed out." 

"  Yes,"  said  Rollo. 

"  What  made  it  ?  "  said  his  father. 

"  Why,  the  water  above  it  was  heavy,  and 
pressed  down  upon  it,  and  crowded  it  out 
through  the  hole." 

"  Yes,"  said  his  father,  "  and  the  deeper 
the  water,  the  more  heavily  it  was  pressed." 

"Yes,  sir,"  said  Rollo,  "and  the  farther  it 
spouted." 

"Because  it  was  pressed  down  by  the 
load  of  such  a  high  column  of  water." 

"  Yes,  sir,"  said  Rollo. 

"  Well,"  replied  his  father,  "  it  is  just  so 
with  the  air.  The  air  all  around  us  is  pressed 
down  by  the  load  of  all  that  is  above  us. 
We  are.  in  fact,  down  at  the  bottom  of  a  great 
ocean  of  air,  and  the  air  here  is  loaded  down 
very  heavy." 

"  How  heavy  ?  "  said  Rollo. 

"  O,  very  heavy  indeed,"  said  his  father. 


PKESSURE.  75 

"  Why,  air  is  pretty  light,"  said  Rollo. 

"Yes,"  replied  his  father,  "  but  then  the 
column  of  it  is  very  high." 

"  How  high  ?  "  said  Rollo. 

"Why,  between  thirty  and  forty  miles. 
But  it  grows  thinner  and  thinner  towards  the 
top  ;  so  it  is  not  as  heavy,  by  any  means,  as  a 
column  of  air  would  be,  thirty  miles  high, 
and  as  dense  all  the  way  up  as  it  is  here." 

"  What  makes  it  grow  thinner  and  thinner 
towards  the  top  ?  "  said  Rollo. 

"  Because,"  said  his  father,  "  that  which  is 
near  the  top,  has  not  as  much  load  of  air 
above  it,  to  press  it  down." 

"  And  that  which  is  at  the  top,"  said 
Rollo,  "has  none  above  it,  to  press  it  down." 

"  No,"  replied  his  father. 

"  And  how  thin  is  it  there  ?  " 

"  Nobody  knows,"  said  his  father. 

"  What,  nobody  at  all  ?  "  said  Nathan. 

"  No,  I  believe  not ;  at  least  I  do  not ;  ana 
I  don't  know  that  any  body  does." 

"  How  do  they  know,  then,  how  high  it 
is  ?  "  said  Rollo. 

"  The  philosophers  have  calculated  in 
some  way  or  other,  though  I  don't  exactly 
know  how.  I  believe  they  have  ascertained 


76 


how  great  the  pressure  of  the  air  is  here  at 
the  surface  of  the  earth,  and  have  calculated 
in  some  way,  from  that,  how  high  the  air 
must  be  to  produce  such  a  pressure." 

"  And  how  high  must  it  be  ?  "  said  Na- 
than. 

"  Why,  between  thirty  and  forty  miles,'5 
said  Rollo  ;  "  father  told  us  once." 

"  And  yet,"  continued  his  father,  "  water, 
thirty  or  forty  feet  deep,  would  produce  as 
great  a  pressure  as  a  column  of  air  of  thirty 
or  forty  miles.  That  is,  the  air  around 
presses  about  as  heavily,  and  would  force  a 
jet  of  air  through  a  hole  with  about  as  much 
force,  as  water  would,  coming  out  at  the 
bottom  of  a  dam,  as  high  as  a  common  three- 
story  house." 

These  explanations  were  all  very  interest- 
ing to  Rollo  and  to  his  mother ;  but  Nathan 
found  it  rather  hard  to  understand  them  all, 
and  he  began  to  be  somewhat  restless  and 
uneasy.  At  length  he  said,  — 

"  And  now,  father,  haven't  you  almost  done 
telling  about  the  air?  " 

"  Why,  yes,"  said  his  father;  "  I  have  told 
you  enough  for  this  time ;  on  y  you  must 
remember  it  all." 


PRESSURE.  77 

"  I  don't  think  I  can  remember  it  quite 
all,"  said  Nathan. 

"  Well,  then,  remember  the  general  prin- 
ciple, at  any  rate,"  said  his  father,  "which 
is  this  —  that  we  live  at  the  bottom  of  a 
vast  ocean  of  air,  and  that  the  lower  portions 
of  this  air  are  pressed  down  by  the  load  of 
all  the  air  above ;  that,  being  so  pressed,  the 
lower  air  is  condensed, — so  that  we  live  in 
the  midst  of  air  that  is  pressed  down,  and 
condensed,  by  the  load  of  all  that  is  above  it  ; 
and  that,  consequently,  whenever  the  air  is 
taken  away,  even  in  part,  from  any  place, 
as  you  removed  some  of  it  from  the  china 
closet,  the  pressure  upon  the  air  outside 
forces  the  air  in  through  every  opening  it 
can  find." 

"  I  think  that  is  a  little  too  much  for  me 
to  remember,"  said  Nathan. 

Nathan's  father  arid  mother  laughed  on 
hearing  this,  though  Nathan  did  not  know 
what  they  were  laughing  at.  His  father 
told  him  that  he  could  not  expect  him  to 
remember  all ;  and  that,  to  pay  him  for  his 
particular  attention,  he  would  tell  him  a 
story. 

So  he  took  Nathan  up  in  his  Jap,  and  told 
7* 


78  AIR. 

him  a  very  curious  story  of  a  boy,  who  went 
about  the  yard  with  a  little  dog  upon  one  of 
his  shoulders,  a  cat  upon  the  other,  and  a 
squirrel  on  his  head.  The  squirrel  was 
tame. 


QUESTIONS. 

Why  cannot  experiments  be  performed  upon  the  pres- 
sure of  air,  as  conveniently  as  upon  the  pressure  of  water  ? 
How  did  Hollo's  father  contrive  to  remove  a  part  of  the  air 
from  the  china  closet?  Where  did  they  expect  that  the 
air  would  be  forced  into  the  closet?  How  were  they  to 
make  this  effect  visible  ?  Did  the  experiment  succeed  ? 
Suppose  the  key-hole  had  been  stopped  up ;  where  would 
the  air  have  been  forced  in  ?  Suppose  all  the  crevices  had 
been  closed.  Is  water  compressible  ?  Is  air  compressi- 
ble '  What  is  the  shape  of  a  cylinder  ?  What  is  a  piston  ? 
How  might  air  be  compressed  by  means  of  a  cylinder  and 
piston  ?  What  was  the  general  principle  which  Kolio  s 
father  stated,  in  conclusion  • 


79 


CHAPTER    VI. 
BALLOONING. 

THE  next  evening,  Hollo  and  Nathan  had 
another  conversation  with  their  father,  re- 
specting air.  When  they  were  all  seated,  he 
commenced  as  follows  :  — 

"  I  told  you  yesterday,  that  air  may  be 
compressed  by  force,  while  water  cannot  be. 
It  has  another  property,  which  is  in  some 
respects  the  reverse  of  this.  It  springs  back 
into  its  original  bulk,  when  the  pressure  is 
removed." 

"  How  ?  "  said  Nathan ;  "  I  don't  exactly 
understand  you." 

"  Why,  you  remember  what  I  said  about 
the  experiment  with  the  iron  cylinder  and  a 
piston  to  fit  it." 

"  Yes,  sir',"  said  Rollo. 

"  What  was  the  experiment  ? "  said  his 
father. 

"  Why.  if  a  man  were  to  press  the  piston 


80  AIR. 

down  hard,  he  could  crowd  the  air  all  into 
the  lower  half  of  the  cylinder." 

"  Yes,"  replied  his  father.  "  Now,  the 
property  I  am  going  to  toll  you  about  this 
evening  is  this  —  that,  if  the  man  lets  go  of  the 
piston  rod,  the  air  that  is  condensed  into  the 
bottom  of  the  cylinder,  will  spring  up,  and 
force  the  piston  up  again.  This  property  is 
called  elasticity.  It  is  sometimes  called  the 
expansive  force  of  the  air.  For  it  is  a  force 
tending  to  expand  the  air,  that  is,  to  swell  it 
out  into  its  original  dimensions.  This  is 
another  great  difference  between  air  and 
water. 

"  Now,  as  all  the  air  around  us,"  continued 
Hollo's  father,  "is  pressed  down  very  heavily, 
and  is  condensed  a  great  deal,  it  is  all  the 
time  endeavoring  to  expand  ;  and  it  would 
expand,  were  it  not  that  the  great  burden  of 
the  air  above  it  keeps  it  condensed.  But 
water  is  not  compressed,  and  has  no  tendency 
to  expand.  The  water  of  Hollo's  dam,  for 
instance,  had  all  the  weight  of  the  atmos- 
phere resting  upon  it,  but  it  did  not  compress 
it  at  all,  and  so  it  did  not  tend  to  expand. 

"And  now,"   said  his  father,   "I  cannot 


BALLOONING. 


perform  any  experiment,  to  show  you  that 
air  tends  strongly  to  expand  or  swell  out  into 
a  great  space,  while  water  does  not ;  but  I 
can  make  a  supposition,  which  will  illustrate 
it.  Suppose  we  had  a  large,  but  very  thin, 
glass  bottle,  filled  with  water,  and  put  dowa 
upon  the  floor  in  the  middle  of  this  room. 
Suppose,  also,  that  we  had  another  bottle,  of 
the  same  size  and  shape,  filled  with  air,  and 
we  put  that  down  upon  the  floor  by  the  side 
of  the  other ;  both  bottles  being  stopped  very 
tight.  Now,  if  we  could  by  any  means  sud- 
denly take  away  all  the  air  from  the  room,  so 
that  there  should  be  nothing  around  the  bot- 
tles, then  the  bottle  of  water  would  remain 
just  as  it  is,  for  the  glass  would  have  nothing 
to  support  but  the  weight  of  the  water,  and  it 
would  be  strong  enough  for  that.  But  the 
bottle  of  air  would  fly  all  to  pieces ;  for  that 
would  not  rest  quietly,  like  the  water,  satis- 
fied with  the  space  which  it  already  has,  and 
only  pressing  with  its  own  weight  upon  the 
sides  of  the  glass ;  but  it  would  immediately 
expand  with  so  much  force  as  to  break  the 
thin  glass  all  to  pieces." 

Would  it !  "  exclaimed  Rollo  and  Nathan 


82 


together.  "  And  would  it  make  a  loud 
noise?" 

"  Yes,"  replied  their  father,  "  I  presume  it 
would  make  a  loud  explosion  ;  that  is,  if  the 
air  in  the  room  around  it  could  by  any 
means  be  all  at  once  and  suddenly  re- 
moved. 

"  And  so  you  must  remember,"  he  con- 
tinued, "  that  there  are  two  very  remarkable 
differences  between  air  and  water.  Air  may 
be  condensed  by  pressure,  and,  as  it  exists 
all  around  us,  is  greatly  condensed  by  the 
pressure  of  the  air  above,  and  it  may  be 
compressed  more.  And  air  is  expansive, 
while  water  is  not.  Whenever  the  pressure 
upon  it  is  removed,  it  suddenly  expands,  or 
spreads  out  in  all  directions." 

"  O  dear  me  !  "  said  Nathan,  with  a  sigh. 

"  What  is  the  matter?  "  said  his  father. 

"Why,  I  can't  understand  it  very  well." 

"  Can't  you  ?  "  said  his  father.  "  Well,  I 
must  admit  that  you  are  rather  too  young  to 
study  pneumatics." 

"  Pneumatics  ?  "  repeated  Rollo. 

"  Yes,"  said  his  father;  "  that  is  the  name 
of  this  science." 


BALLOONING.  85 

"  What,  the  science  of  air  ? "  said  Rollo. 

"  Yes,"  said  his  father,  "  the  science  which 
treats  of  air,  and  ef  all  other  compressible 
and  expansive  fluids.  But  let  me  think.  I 
must  try  to  tell  you  something  which  Nathan 
can  understand  and  be  interested  in.  If  I 
had  a  very  light  feather,  I  could  let  him 
perform  an  experiment." 

"Would  a  little  down  do?"  said  Hollo's 
mother. 

"  Yes,"  replied  his  father,  "  that  would  be 
better  than  a  feather." 

•Mrs.  Holiday  then  went  and  brought  a 
little  down,  and  handed  it  to  Hollo's  father. 
Now,  there  was  a  lamp  upon  the  table,  of  a 
peculiar  kind,  called  a  study  lamp.  It  had 
a  glass  tube,  called  a  chimney,  around  the 
wick,  and  consequently  around  the  flame 
itself,  being  round,  like  a  ring. 

Hollo's  father  told  Nathan  to  hold  the 
down  over  the  top  of  this  glass  chimney, 
and  then  to  let  it  go. 

Nathan  did  so.  The  little  tuft  of  down 
was  wafted  up  into  the  air,  quite  high  above 
the  lamp,  and  then  it  sailed  slowly  away,  and 
fell  down  upon  the  table.  t 


"  I  know  what  makes  it  rise,"  said  Hollo. 
"It  is  the  heat.  The  heat  makes  it  rise." 

"Do  you  think  so?"  said  his  father. 
"Then  take  the  down,  and  lay  it  gently 
upon  the  hearth,  before  the  fire,  as  near  as 
you  can." 

Rollo  did  so.  He  had  to  take  his  hand 
away  very  quick,  for  it  was  quite  hot  there. 
The  little  tuft  remained  quietly  upon  the 
hearth  where  he  placed  it. 

"There,"  said  his  father,  "is  not  that  a 
hotter  place  than  it  was  over  the  lamp?  " 

"  Yes,  sir,"  said  Rollo. 

"  Then,  if  it  was  heat  that  made  it  rise, 
why  does  not  it  rise  now  ?  " 

Rollo  could  not  tell. 

"  I  will  tell  you  how  it  was,"  said  his 
father.  "Heat  makes  air  more  expansive. 
When  air  is  heated,  it  swells;  when  it  is 
cool,  it  shrinks  again.  Now,  if  it  swells,  it 
becomes  lighter,  and  so  it  is  buoyed  up  by 
the  heavier  air  around  it ;  just  as  wood  at 
the  bottom  of  the  sea  would  be  buoyed  up, 
and  would  rise  to  the  surface  of  the  water. 
Now,  the  heat  of  the  lamp  heats  the  air  that 
is  in  the  glass  chimney,  and  swells  it.  This 


BALLOONING  8? 

makes  it  lighter ;  and  so  the  air  around  it, 
which  is  heavier,  buoys  it  up,  and  it  carries 
up  the  feather  with  it." 

"  No,  the  down,  father,"  said  Nathan. 

11  Yes,  the  down,"  said  his  father. 

"  Then  it  seems  to  me,  after  all,"  said 
Rollo,  "  that  it  is  the  heat  which  makes  it 
rise." 

"  Yes,"  said  his  father,  "it  does,  indirectly. 
It  expands  the  air;  that  makes  it  lighter; 
then  the  heavy  air  around  it  buoys  it  up, 
and,  when  it  goes  up,  it  carries  up  the  down. 
So  that  it  is  riot  strictly  correct  to  say,  that 
the  heat  carries  it  up.  The  heat  sets  in 
operation  a  train  of  causes  and  effects,  the 
last  of  which  results  in  carrying  up  the 
feather. 

"Now,"  continued  his  father,  "there  is 
always  a  stream  of  air  going  up,  wherever 
there  is  a  lamp,  or  a  fire,  or  heat,  which 
heats  the  air  in  any  way.  The  expanded 
air  from  a  fire  goes  up  chimney.  The  cool 
and  heavy  air  in  the  room  and  out  of  doors 
crowds  it  up." 

"The  air  out  of  doors?"  said  Rollo. 
"  How  can  that  crowd  it  up  ?  " 

"  Why,  it  presses  in  through  all  the  crev- 


88  AIR. 

ices  and  openings  all  around  the  room,  and 
crowds  the  light  air  up  the  chimney.  All 
the  smoke  is  carried  up  too  with  it,  and  it 
comes  pouring  out  at  the  top  of  the  chimney 
all  the  time." 

"  You  can  see  that  the  air  presses  in  at 
ill  these  crevices,"  continued  Hollo's  father, 
"  by  experiment." 

"  What  experiment  is  it  ?  "  said  Hollo  ;  "let 
us  try  it." 

"  I  will  let  Nathan  try  it,"  said  his  father, 
"and  you  may  go  with  him  and  see  the 
effect.  First,"  he  continued,  "  you  see  by  the 
smoke,  that  the  air  really  goes  up  the  chim- 
ney ;  and  I  will  show  you  that  other  air 
really  crowds  into  the  space,  from  other 
parts  of  the  room." 

So  he  took  a  lamp  from  the  table, — not 
the  study  lamp ;  it  was  a  common  lamp,  — 
and  held  it  at  various  places  in  the  opening 
of  the  fireplace,  by  the  jambs  and  near  the 
upper  part ;  and  Rollo  and  Nathan  saw  that 
the  flame,  in  all  cases,  was  turned  in  towards 
the  chimney. 

"  Yes,"  said  Rollo,  "  I  see  it  is  drawn 
in." 

"  No,''  said  his  father  ;  "  strictly  speaking,  if 


BALLOONING.  89 

s  not  drawn  in;    it   is   pressed  in,  by  the 
cool  and  heavy  air  of  the  room." 

"I  thought,"  said  Hollo's  mother,  "that 
the  chimney  drew  the  air  from  the  room 
into  it." 

"  That  is  what  is  generally  said,"  replied 
Mr.  Holiday,  "  but  it  is  not  strictly  true. 
The  common  idea  is,  that  the  hot  air  rises  in 
the  chimney,  and  so  draws  the  air  from  the 
room  to  supply  its  place  ;  but  this  is  not  so. 
In  the  first  place,  nothing  can  rise  unless  it  is 
forced  up.  The  lightest  things  have  some 
weight,  and  would,  if  left  to  themselves,  fall. 
The  hottest  and  lightest  air  in  a  chimney 
would  fall  to  the  earth,  if  there  was  no  cooler 
and  heavier  air  around  it,  to  force  it  to  rise ; 
—  just  as  the  lightest  cork,  which  would  rise 
very  quick  from  the  bottom  of  the  sea,  would 
fall  back  again  very  quick,  if  the  water  was 
not  there. 

"  Remember,  then,  Nathan  and  Rollo,  that, 
when  a  fire  is  built  in  a  fireplace,  so  as  to 
warm  the  air  in  the  chimney,  it  makes  this 
air  not  so  heavy ;  and  then  the  cool  air 
All  around  it  in  the  room  and  out  of  doors, 
presses  in,  and  crowds  under  the  light  air. 
*nd  makes  it  ascend." 
d*  S* 


90  AIR. 

"But,  father,"  said  Nathan,  "you  said  I 
might  perform  an  experiment." 

"  Very  well,  I  am  ready  now.  Take  the 
lamp,  and  carry  it  around  the  room,  and  hold 
it  opposite  any  little  opening  you  can  find." 

"  I  can't  find  any  little  openings,"  said 
Nathan. 

"  O  yes,"  said  his  father ;  "  the  key-hole 
of  the  door  is  a  little  opening,  and  there  is  a 
narrow  crevice  all  around  the  door ;  and 
you  will  find  little  crevices  around  the 
windo\vs.  Now,  hold  the  lamp  opposite  any 
of  these,  and  you  will  see  that  the  air  presses 
in." 

So  Nathan  went  with  the  lamp,  Hollo  fol- 
lowing him,  and  held  the  lamp  opposite  to 
the  key-hole,  and  the  crevices  around  the 
door  and  windows ;  only,  when  he  came  to 
the  window,  his  father  told  him  to  be  very 
careful  not  to  set  the  curtain  on  fire. 

Hollo  wanted  Nathan  to  let  him  try  it 
once  ;  and  so  Nathan  gave  him  the  lamp. 
He  said  he  meant  to  make  a  crevice ;  and  so 
he  pushed  up  the  window  a  very  little  way, 
and  held  the  lamp  opposite  to  the  opening. 
The  air  pressed  the  flame  in  towards  the 
room,  in  all  cases. 


BALLOONING.  91 

"People  commonly  say,  that  it  is  drawn 
in,"  said  his  father,  "  but  that  is  not  strictly 
correct ;  it  is  really  pressed  in.  There  is  no 
power  of  attraction,  in  the  air  that  is  in  the 
room,  to  draw  in  the  air  that  is  out  of  doors, 
through  the  crevices ;  but  the  air  that  is 
out  of  doors,  is  so  heavy,  that  it  presses  in, 
and  crowds  the  ^jvarm  and  light  air  up  the 
chimney. 

"  And  now,"  said  his  father,  "  I  cannot 
tell  you  anything  more  this  evening ;  but,  if 
you  remember  this,  I  will  give  you  some 
further  instruction  another  time." 

"Well,  sir,"  said  Nathan,  "only  I  wish 
you  would  tell  me  a  little  story,  as  you  did 
last  evening.  Have  not  I  been  still  ?  " 

His  father  had  noticed,  that  he  had  been 
very  still  and  attentive,  but  did  not  think 
before,  that  it  was  in  expectation  of  being 
rewarded  with  a  story. 

"  Well,"  said  his  father,  "  I  will  tell  you 
a  story,  or  give  you  a  little  advice.  How 
should  you  like  a  little  advice  ?  " 

"  Well,  father,  a  little  advice ;  just  which 
you  please." 

"  I  advise  you,  then,  — let  me  see,  —  what 
shall  I  advise  you  ?  —  No,  on  the  whole.  I 


will  tell  you  a  story.  Once  there  was  a  man, 
and  he  was  a  philosopher.  He  understood 
all  that  I  have  been  explaining  to  you  about 
the  air  being  light  when  it  was  hot.  So  he 
got  some  very  thin  paper,  and  made  a  large 
paper  bag.  He  cut  the  paper  very  curiously, 
and  pasted  it  together  at  the  edges  in  such  a 
way,  that  the  bag,  when^it  was  done,  was 
round,  like  a  ball ;  and  it  had  a  round  opening 
at  the  bottom  of  it.  In  fact,  it  was  a  large 
paper  ball." 

"  How  large  was  it  ?  "  said  Nathan. 

"  It  was  so  large,  that,  when  it  was 
swelled  out  full,  it  would  have  been  higher 
than  your  head." 

"  O,  what  a  large  ball !  "  said  Nathan. 
"  But  what  was  it  for  ?  " 

"  Why,  the  man  thought,  as  hot  air  is 
lighter  than  cool  air,  and  floats  up,  that  per- 
haps, if  he  could  fill  his  paper  ball  with  hot 
air,  it  would  go  up  too." 

"  And  did  it  ?  "  said  Nathan. 

"Yes,"  said  his  father.  "He  filled  it 
with  hot  air ;  and  the  hot  air  was  so  light, 
that  it  rose  up  and  carried  the  paper  ball 
with  it." 


BALLOONING.  93 

"  How  did  he  get  the  hot  air  into  it  ? " 
said  Rollo. 

"  Why,  he  held  it  over  a  little  fire,  with 
the  mouth  down.  Then  the  hot  air  from 
the  fire  went  up  into  the  ball,  and  swelled  it 
out  full." 

"  How  high  did  it  go  ?  "  said  Nathan. 

"  O,  it  soared  away,"  said  his  father, 
"away  up  into  the  air,  very  high;  until  at 
length  it  got  cool,  and  then  it  came  down." 

"  I  should  like  to  see  such  a  ball  as  that," 
said  Nathan. 

"  Such  a  ball  as  that  is  called  a  balloon," 
said  his  father. 

"  I  wish  I  could  see  a  balloon,"  said 
Nathan. 


QUESTIONS. 

What  is  the  important  difference  between  air  and  water, 
which  was  explained  in  the  last  chapter,  and  mentioned  in 
this  ?  Does  the  air  tend  to  expand  again  after  it  is  com- 
pressed ?  What  is  this  property  of  the  air  called  ?  Is  the 
air  around  us  already  condensed,  or  is  it  in  its  natural 
state  ?  What  causes  it  to  be  condensed  ?  Suppose  a  thin 
glass  vessel  were  to  be  filled  with  air,  and  another  with 
water,  and  the  air  suddenly  removed  from  the  room  around 
them  ;  what  would  be  the  effects  ?  What  effect  does  heat 
bave  upon  the  expansibility  of  air?  How  may  this  effect 
be  made  to  appear  over  a  lamp  ?  In  a  chimney  '  What 
was  the  story  which  Hollo's  father  told  Nathan  ? 


94 


CHAPTER    VII. 

PHILOSOPHICAL    DISCUSSION. 

SOME  time  after  this,  Rollo,  and  Nathan, 
and  James,  were  playing  in  the  shed,  one 
pleasant  morning  in  the  spring.  They  were 
building  with  sticks  of  wood,  which  they 
piled  in  various  ways,  so  as  to  make  houses. 
They  took  care  not  to  pile  the  wood,  in  any 
case,  higher  than  their  shoulders,  for  Jonas 
had  told  them  that,  if  they  piled  the  wood 
higher  than  that,  there  would  be  danger  of 
its  falling  down  upon  them. 

After  some  time,  Rollo  went  into  the 
house  a  few  minutes,  and  James  and  Nathan 
went  to  the  open  part  of  the  shed,  and  began 
to  look  out  of  doors.  The  sun  was  shining 
pleasantly,  but  the  ground  was  wet,  being 
covered  with  streams  and  pools  of  water,  and 
melting  snow-banks. 

"  What  a  pleasant  day  !  "  said  James.  "  I 
wish  it  was  dry,  so  that  we  could  go  out 
better." 


PHILOSOPHICAL    DISCUSSION.  95 

"  I  wish  we  could  fly,"  said  Nathan,  "  for 
it  is  very  pleasant  up  in  the  air." 

"  I  wish  we  had  a  balloon,"  said  James. 
"  If  we  had  a  balloon,  we  could  go  up  in  the 
air,  easier  than  to  fly." 

"  O  James,"  said  Nathan,  "  you  could  not 
get  into  a  balloon  if  you  had  one." 

"  Why  not  ?  "  said  James. 

"  Because,"  said  Nathan,  "  it  would  not  be 
big  enough." 

"Why,  Nathan,"  said  James,  "a  balloon 
is  bigger  than  this  house." 

"  O  James,  it  is  not  higher  than  my  head." 

"It  is,"  said  James,  "I  know  it  is.  I 
have  read  about  balloons  bigger  than  a 
house." 

"And  my  father,"  said  Nathan,  putting 
down  his  foot  in  a  very  positive  air,  "  my 
father  told  me  himself,  that  a  balloon  was 
about  as  high  as  my  head." 

The  boys  disputed  some  time  longer  upon 
the  subject,  and  finally,  when  Rollo  came  out 
of  the  house,  they  both  appealed  to  him  very 
eagerly  to  settle  the  dispute. 

"Isn't  a  balloon  higher  than  Nathan's 
head  ?  "  said  James. 

"Is  it  as  high  as  a  house  ? "  said  Nathan, 


96  AIR. 

"  Why,  I  know,"  said  Rollo,  "  that  a  man 
made  a  balloon  once  about  as  high  as 
Nathan's  head,  because  my  father  said  so; 
but  perhaps  it  was  a  little  one." 

"  Yes,"  said  James,  "  I  know  it  must  be  a 
little  one ;  for  balloons  are  big  enough  for 
men  to  go  up  in  them." 

"  O  James,"  said  Nathan,  "  I  don't  believe 
it.  Besides,  the  fire  would  burn  'em." 

"  What  fire  ?  "  said  James. 

"  The  fire  they  burn  under  the  balloons,  to 
make  the  air  hot,"  said  Nathan. 

"  I  don't  believe  they  have  any  fire,"  said 
James. 

Just  then  Nathan,  happening  to  look  around, 
saw  Jonas  standing  behind  them  ;  he  had  just 
come  out  of  the  house,  and  was  going  out  to 
his  work.  Hearing  the  boys  engaged  in  this 
dispute,  he  stopped  to  listen.  The  boys  both 
appealed  to  Jonas. 

Jonas  heard  all  that  they  had  to  say,  and 
then  replied,  — 

"  I  cannot  tell  you  much  about  going  up 
in  a  balloon,  but  I  can  tell  you  something 
about  getting  along  pleasantly  down  here 
upon  the  earth,  which  I  think  may  be  of 
service  to  you." 


PHILOSOPHICAL    DISCUSSION.  97 

"  What  is  it  ?  "  said  James. 

"  Why,  that  you  will  neither  of  you  get 
along  very  pleasantly  until  you  can  bear  to 
have  any  body  else  mistaken,  without  con- 
tradicting them.  James,  you  think  Nathan 
is  mistaken  about  the  size  of  a  balloon,  do 
you  ? " 

"Yes,  I  know  he  is,"  said  James. 

"Well,"  said  Jonas,  "now  why  not  let 
him  remain  mistaken  ?  " 

"  Why,  —  I  don't  know,"  said  James. 

"  He  isn't  willing  to  be  convinced,  is  he. 
that  a  balloon  is  as  big  as  a  house  ?  " 

"No,"  said  James,  "he  is  not." 

"  Then  why  don't  you  let  him  remain  un- 
convinced ?  Why  should  you  insist  on  set- 
ting him  right,  when  he  don't  want  to  be  set 
right  ? " 

"  And  you,  Nathan,  suppose  that  James  is 
mistaken,  in  thinking  that  the  balloon  is  so 
big." 

"  Yes,"  said  Nathan,  "  and  that  men  can 
get  into  it,  and  go  up  in  the  air." 

"  Well,  now,  if  he  wants  to  believe  that 
balloons  are  so  big,  why  are  you  not  willing 
that  he  should  ?  Why  should  you  insist 
e  9 


98  AIR. 

upon  it  that  he  should  know  that  tl  ey  are 
smaller?" 

"  Because  I  know"  said  Nathan,  very  posi- 
tively, "  that  they  are  small ;  and,  besides, 
the  paper  would  not  be  strong  enough  to 
bear  a  man." 

"  I  did  not  ask  you,"  said  Jonas,  "  why 
you  believed  that  men  could  not  go  up  in 
balloons,  but  why  you  were  so  anxious  to 
make  James  believe  so.  Why  not  let  him 
be  mistaken  ? " 

"  Why  —  because,"  said  Nathan. 

"  You  see,  Nathan,"  continued  Jonas,  "  the 
world  is  full  of  people  that  are  continually 
mistaken ;  and  if  you  go  about  trying  to  set 
them  all  right  by  disputing  them,  you'll  have 
a  hard  row  to  hoe." 

"  A  hard  what  ? "  said  Nathan. 

"  A  hard  row  to  hoe,"  repeated  Jonas. 
"  It's  never  of  any  service  to  attempt  to  con- 
vince people  that  don't  want  to  be  con- 
vinced; especially  if  they  are  wrong." 

"  Especially  if  they  are  wrong  !  "  repeated 
Rollo,  in  astonishment. 

"  Yes,"  replied  Jonas.  "  The  very  worst 
time  to  argue  with  a  boy,  is  when  he  is 


PHILOSOPHICAL    DISCUSSION.  99 

wrong,  and  does  not  want  to  be  set  ngnt. 
It  is  a  great  deal  harder  to  get  along  in  argu- 
ment with  one  who  is  right,  than  with  one 
who  is  wrong  j  for  the  one  who  is  wrong, 
disputes;  the  one  who  is  right,  reasons." 

"Well,  Jonas,"  said  James,  "which  of  us 
was  disputing  ? " 

"  Both  of  you,"  said  Jonas. 

"  Both  of  us,"  said  James ;  "but  y*U  said 
that  only  the  one  who  was  wrong,  dis- 
puted." 

"Well,"  replied  Jonas,  "you  were  both 
wrong." 

"  Both  wrong  !  O  Jonas !  "  said  James. 

"  Yes,  both  wrong,"  replied  Jonas ;  and  so 
saying,  he  was  going  away  to  his  work. 

"  But  stop  a  minute  longer,"  said  James, 
"  and  tell  us  how  it  is  about  the  balloon ; 
we  want  to  know." 

"  O  no,"  said  Jonas,  "  you  don't  want  to 
know  ;  you  want  to  conquer" 

"  What  do  you  mean  by  that  ?  "  said  Na- 
than. 

"  Why,  you  don't  really  wish  to  learn  any 
thing ;  but  you  want  to  have  me  decide  the 
case,  because  each  of  you  hopes  that  I  shall 
decide  in  his  favor.  You  want  the  pleasure 


tOO  AIR. 

of  a  victory,  not  the  pleasure  of  acquiring 
knowledge." 

"  No,  Jonas,"  said  Nathan,  "  we  do  really 
want  to  know." 

"  Well,"  said  Jonas,  "  I  can't  stop  now  to 
tell  you ;  perhaps  I  will  this  evening ;  but  I 
advise  you  always,  after  this,  not  to  contradict 
people,  and  dispute  with  them,  when  they 
say  thiftgs  that  you  don't  believe.  Do  as 
the  gentleman  did,  when  the  man  said  the 
moon  was  a  fire." 

"  What  did  he  do  ?  "  said  Hollo. 

"  Why,  he  let  him  say  it  as  much  as  he 
wanted  to." 

"  Tell  us  all  about  it,"  said  James. 

"Well,  then,"  said  Jonas,  "once  there 
was  a  man,  and  he  saw  the  moon  coming  up 
behind  the  trees,  and  thought  it  was  a  large 
house  burning  up.  He  went  along  a  little 
way,  and  he  met  a  vulgar  fellow,  riding  in  a 
carriage." 

"  Riding  in  a  carriage  !  "  repeated  Hollo, 
astonished. 

"  Yes,"  said  Jonas,  "  handsomely  dressed. 
•'  Sir,'  said  the  man,  '  see  that  great  fire  !  ' 

"  '  It  isn't  a  fire,  you  fool,'  said  the  vulgar 
fellow  ;  '  it's  nothing  but  the  moon.' 


PHILOSOPHICAL    DISCUSSION.  101 

"  {  The  moon !  no  it  isn't,'  said  the  man  ; 
'it  is  a  monstrous  great  fire.  Don't  you  see 
how  it  blazes  up  ? ' 

"  l  It  is  not  a  fire,  I  tell  you/  said  the  vul- 
gar fellow. 

"  '  I  tell  you  'tis,'  said  the  man. 

"'You  don't  know  any  thing  about  it,' 
said  the  vulgar  fellow. 

"  'And  you  don't  know  the  moon  from  a 
house  on  fire,'  said  the  man,  and  so  passed  on. 

"  A  minute  or  two  after  this,  he  met  a 
gentleman  driving  a  team. 

"A  gentleman  driving  a  team!"  said 
James. 

"Yes,"  said  Jonas,  "with  a  frock  on. 
He  was  tired  and  weary,  having  driven  all 
day.  The  man  asked  him  if.  he  did  not  see 
that  house  on  fire. 

"'Ah,'  said  the  gentleman,  <I  thought  it 
was  the  moon.' 

"  '  No,'  said  the  man, '  it  is  a  house  on  fire.' 

"  '  Well,'  said  the  gentleman,  '  I  am  very 
sorry  if  it  is.  I  hope  they'll  be  able  to  put 
it  out ! ' 

"  So  saying,  he  started  his  team  along,  and 
bade  the  man  good  evening." 

Jonas  then,  having  finished  his  story, 
9* 


102  AIR. 

stepped  out  of  the  shed,  and  went  along  to- 
wards the  barn  ;  Nathan  called  out  after  him 
to  say,  — 

"  Well,  Jonas,  I  don't  understand  how  the 
gentleman  came  to  be  driving  a  team  all 
day." 

Jonas  did  not  reply  to  this,  but  only  began 
to  laugh  heartily,  and  to  walk  on.  Nathan 
turned  back  into  the  shed,  saying,  he  did  not 
see  what  Jonas  was  laughing  at. 

The  boys  wanted  very  much  to  have  the 
question  about  the  balloon  settled ;  and,  after 
some  further  conversation  on  the  subject, 
they  concluded  to  go  in  and  ask  their  mother. 
So  they  all  three  went  in.  Hollo  proposed 
this  plan,  and  he  led  the  way  into  the  house. 
He  found  his  mother  sitting  in  the  parlor  at 
her  work. 

"Well,  boys,"  said  she,  "have  you  got 
tired  of  your  play?" 

"  No,  mother,"  said  Hollo,  "  but  we  want 
to  know  about  balloons :  how  big  are 
they?" 

"  O,  some  of  them,"  said  she,  "  are  very 
large." 

"Ain't  they  as  big  as  this  house?"  said 
James. 


PHILOSOPHICAL    DISCUSSION.  103 

"Yes,  I  believe  they  have  been  made  as 
big,"  said  she. 

"  But,  mother,"  said  Nathan,  "  father  told 
me,  his  very  self,  that  they  were  no  higher 
than  my  head." 

"  O  no,"  said  his  mother  ;  "  he  said  that  a 
man  made  one  which  was  about  as  high  as 
your  head ;  but  that  was  only  a  little  one, 
for  experiment.  When  they  make  large 
ones,  for  use,  they  are  as  high  as  this  house." 

"  For  use,  mother  ?  what  use  ?  "  said  Na- 
than. 

"  Men  go  up  in  them,  don't  they,  aunt  •*  " 
said  James. 

"  Not  in  them,  exactly,"  said  his  aunt. 
"  They  could  not  live  in  them,  but  they  go 
up  by  means  of  them." 

"  How  ? "  said  Nathan. 

"  Why,  they  have  a  kind  of  basket,  which 
hangs  down  below  the  balloon,  and  they  get 
into  that." 

"  I  knew  they  could  not  get  into  the 
balloon,"  said  Nathan. 

"  Then  you  have  had  a  dispute  about 
it,"  said  his  mother. 

"Why,  —  yes,"  said  Nathan,  with  hesita- 
tion, "we  disputed  a  little." 


IU4 


"  1  am  sorry  to  hear  that,"  said  his  mother, 
for  disputing  seldom  does  any  good.  The 
fact  is,  however,  that  men  have  often  been 
carried  up  by  balloons,  but  they  never  gel 
into  them.  They  could  not  live  in  them. 
They  could  not  breathe  the  kind  of  air  which 
balloons  are  filled  with." 

"  It  is  hot  air,"  said  Nathan. 

"No,"  said  his  mother,  "the  kind  of  bal- 
loon which  your  father  told  you  of  was 
filled  with  hot  air ;  but  the  balloons  which 
people  generally  use  to  go  up  with,  are 
filled  with  another  kind  of  air,  which  is 
very  light  when  it  is  cool.  They  make  an 
enormous  bag  of  silk,  and  fill  it  with  this 
light  air,  which  they  make  in  barrels ;  and 
then,  when  the  bag  is  filled,  it  floats  away 
above  their  heads,  and  pulls  hard  upon  the 
fastening.  There  is  a  net  all  over  it,  and 
the  ends  of  the  net  are  drawn  together  be- 
low, and  are  fastened  to  the  basket,  or  car, 
where  the  man  is  to  sit.  When  it  is  all 
ready,  the  man  gets  into  the  car,  and  then 
they  let  go  the  fastenings,  and  away  the 
great  bag  goes,  and  carries  the  man  with  it. 
away  up  into  the  air." 


PHILOSOPHICAL    DISCUSSION.  105 

"  And  then  how  does  he  get  down?  "  said 
Nathan. 

"  Why,  he  can  open  a  hole  in  the  bag,  and 
let  some  of  the  light  air  out :  and  then  he 
begins  to  come  down  slowly.  If  he  conies 
down  too  fast,  or  if  he  finds  that  he  is  com- 
ing into  the  water,  or  down  upon  any  dan- 
gerous place,  there  is  a  way  by  which  he 
can  make  his  balloon  go  up  again." 

"  What  way  is  it,  aunt  ?  "  said  James. 

"  Why,  he  has  some  bags  of  sand  in  hib 
balloon,"  said  his  aunt ;  "  and  the  balloon  is 
made  large  enough  to  carry  him  and  his  sand- 
bags too.  Then,  if  he  finds  that  he  is  com- 
ing down  too  fast,  he  just  pours  out  some  of 
his  sand,  and  that  makes  his  car  lighter ;  and 
so  the  balloon  will  carry  him  up  again." 

"  That's  a  good  plan,"  said  Rollo. 

"  Yes,"  said  his  mother ;  "  the  reason  why 
he  takes  sand  is,  because  that  will  not  hurt 
any  body  by  falling  upon  them.  If  he 
should  take  stones,  or  any  other  heavy,  solid 
things,  and  should  drop  them  out  of  his  car, 
they  might  possibly  fall  upon  some  body,  and 
hurt  them.  So  he  takes  sand  in  bags,  and, 
when  he  wants  to  lighten  his  balloon,  he  just 
pours  the  sand  out." 


106 


Hollo's  mother  then  told  the  boys  that 
there  was  a  large  book,  which  had  several 
stories  in  it  of  men's  going  up  in  balloons, 
and  that  she  would  get  it  for  them.  So  she 
left  her  work,  and  went  out  of  the  room  ;  but 
in  a  few  minutes  she  returned,  bringing  with 
her  two  very  large,  square  books,  with  blue 
covers.  One  of  them  had  pictures  in  it,  and 
among  the  rest  there  were  pictures  of  bal- 
loons. She  opened  the  other  book,  and 
found  the  place  where  there  was  an  account 
of  balloors,  and  she  showed  the  place  to 
Rollo. 

She  told  the  boys  that  they  had  better 
go  out  in  the  kitchen,  or  into  the  shed,  if  it 
was  warm  enough,  and  read  the  account. 

"  You  and  James,  Rollo,"  said  she,  "  can 
read  by  turns,  and  let  Nathan  hear.  Then, 
when  the  plates  are  referred  to,  you  must 
'ook  into  tne  other  book  and  find  them." 

"Yes,"  said  Rollo,  "we  will;  only, 
mother,  if  you  would  let  us  sit  down  here 
and  read  it  —  and  then,  if  there  is  any  thing 
which  we  cannot  understand,  you  can  tell 
us  what  it  means." 

"  Very  well,"  replied  his  mother,  "  you 
may  sit  down  here  upon  the  sofa." 


PHILOSOPHICAL    DISCUSSION.  10? 

So  the  hoys  sat  down  upon  the  sofa. 
They  put  Nathan  between  them,  so  that  he 
might  look  over.  Rollo  and  James  took 
turns  to  read,  and  they  continued  reading 
about  balloons  for  more  than  an  hour.  There 
was  one  story  of  a  sheep,  which  a  man  car- 
ried up  in  his  car,  under  a  balloon,  and  then  let 
him  drop,  from  a  great  height,  with  a  para- 
chute over  his  head,  to  make  him  fall  gently. 
And  he  did  fall  gently.  He  came  down  to 
the  ground  without  being  hurt  at  all. 


QUESTIONS. 

How  was  the  subject  of  balloons  introduced  into  the  con- 
versation ?  What  was  Nathan's  opinion  about  the  possi- 
bility of  being  carried  up  by  a  balloon?  What  was  the 
dispute  about  the  size  of  balloons  ?  What  was  Nathan's 
evidence  ?  What  was  James's  evidence  ?  What  did 
Jonas  say  when  they  appealed  to  him  ?  What  was  the 
story  that  he  related  ?  Which  of  the  boys  did  he  finally 
say  was  wrong  ?  Whom  did  the  boys  appeal  to  afterwards  ' 
What  did  Hollo's  mother  say  about  the  size  of  balloons? 
How  did  she  say  that  large  balloons  were  filled  ?  How  can 
they  make  the  balloon  come  down  ?  How  can  they  make 
it  go  up  again,  if  they  wish  to  do  so  ? 


108 


CHAPTER    VIII. 

TASKS. 

A  FEW  days  after  this,  there  commenced  a 
ong  storm  of  rain.  Hollo  and  Nathan  were 
glad  to  see  it  on  one  account,  for  their  moth- 
er told  them  it  would  melt  away  the  snow, 
and  bring  on  the  spring.  The  first  day,  they 
amused  themselves  pretty  well,  during  their 
play  hours,  in  the  shed  and  in  the  garret ; 
but  on  the  second  day,  they  began  to  be  tired. 
Nathan  came  two  or  three  times  to  his 
mother,  to  ask  her  what  he  should  do ;  and 
Rollo  himself,  though,sbeing  older,  his  re- 
sources might  naturally  be  expected  to  be 
greater,  seemed  to  be  out  of  employment. 

At  last,  their  mother  proposed  that  they 
should  come  and  sit  down  by  her,  and  she 
would  tell  them  something  more  about  the 
air.  "  How  should  you  like  that,  Rollo  ?  " 
said  she. 

"Why,  pretty  well,"  said  Rollo;  but  he 
spoke  in  an  indifferent  and  hesitating  man- 


ner,  which  showed  that  he  did  not  feel  much 
interest  in  his  mother's  proposal. 

"  /  can't  understand  very  well  about  the 
air,"  said  Nathan. 

Their  mother,  finding  that  the  boys  did 
not  wish  much  to  hear  any  conversation 
about  the  air,  said  nothing  more  about  it  just 
then,  and  Hollo  and  Nathan  got  some  books, 
and  began  to  read ;  but  somehow  or  other, 
they  did  not  find  the  books  very  interesting, 
and  Rollo,  after  reading  a  little  while,  put 
down  his  book,  and  went  to  the  window, 
saying  that  he  wished  it  would  stop  raining. 
Nathan  followed  him,  and  they  both  looked 
out  of  the  window  with  a  weary  and  discon- 
solate air. 

Their  mother  looked  at  them,  and  then 
said  to  herself,  "  They  have  not  energy  and 
decision  enough  to  set  themselves  about 
something  useful,  and  in  fact  1  ought  not  to 
expect  that  they  should  have.  I  must  supply 
the  want,  by  my  energy  and  decision." 

Then  she  said  aloud  to  Rollo  and  Na- 
than, — 

"I  want  you,  boys,  to  go  up  into  the 
garret,  and  under  the  sky-light  you  will  see 
A  large  box.  Open  this  box,  and  you  will 
10 


110  AIR. 

find  it  filled  with  feathers.  Select  from 
these  feathers  three  or  four  which  are  the 
most  downy  and  soft  about  the  stem,  and 
bring  them  down  to  me." 

"  What  are  they  for  ?  "  said  Hollo. 

"I  will  tell  you,"  replied  his  mother, 
"  when  you  have  brought  them  to  me." 

So  Rollo  and  Nathan  went  up  into  the 
garret,  and  brought  the  feathers.  They 
carried  them  to  their  mother.  She  said  that 
they  would  ansAver  very  well,  and  she  laid 
them  gently  down  upon  the  table. 

Then  she  took  up  her  scissors,  and  began 
to  cut  off  some  of  the  lightest  down,  saying, 
at  the  same  time,  — 

"  Now,  children,  I  am  going  to  give  you 
some  writing  to  do,  about  the  az'r." 

"  Writing  ?  "  said  Rollo. 

"  Yes,"  said  his  mother.  "  I  am  going  to 
explain  to  you  something  about  the  air,  and 
then  you  must  write  down  what  I  tell  you." 

"  But  I  can't  write,"  said  Nathan. 

"No,"  said  his  mother,  "but  you  can  tell 
Rollo  what  you  would  wish  to  say,  and  he 
will  write  it  for  you." 

"Why,  mother,"  said  Rollo,  "I  don't 
think  that  that  will  be  very  good  play.1' 


TASKS.  Ill 

"  No,"  replied  his  mother,  "  1  don't  give  it 
to  you  for  play.  It  will  be  quite  hard  work 
I  hope  you  will  take  hold  of  it  energetically, 
and  do  it  well. 

"  First,"  said  she,  "I  am  going  to  perform 
some  experiments  for  you,  before  I  tell  you 
what  I  want  you  to  write." 

By  this  time,  she  had  cut  off  the  downy 
part  of  several  feathers,  and  had  laid  them 
together  in  a  little  heap.  Then  she  took  a 
fine  thread,  and  tied  this  little  tuft  of  down 
to  the  end  of  it.  Then  she  took  up  the 
thread  by  the  other  end,  and  handed  it  to 
Rollo. 

"  There,  Rollo,"  said  she.  "  Now,  do  you 
remember  what  your  father  told  you,  the 
other  day,  about  the  effect  of  heat  upon 
air?" 

"  It  makes  it  light,"  said  Rollo. 

"  And  why  does  it  make  it  light  ?  "  asked 
his  mother. 

"Why,  I  don't  exactly  recollect,"  said 
Rollo. 

"  Because  it  swells  it ;  it  makes  it  expand  ; 
so  that  the  same  quantity  of  air  spreads  over 
a  greater  space ;  and  this  makes  it  lighter, 


112  AIR. 

But  cool  or  cold  air  is  heavier,  because  it  is 
more  condensed. 

"  Now,  wherever  there  is  heat,"  continued 
his  mother,  "  the  air  is  made  lighter,  and  the 
cool  and  heavy  air  around  presses  in  under 
it,  and  buoys  it  up.  This  produces  currents 
of  air.  You  recollect,  don't  you,  that  your 
father  explained  all  this  to  you  the  other  day  ?  " 

"  Yes,"  said  Rollo,  "  I  remember  it." 

"  Well,"  said  his  mother,  "  now  you  and 
Nathan  may  take  this  little  tuft,  and  carry  it 
about  to  various  places,  and  hold  it  up  by  its 
thread,  and  it  will  show  you  the  way  the  air 
is  moving ;  and  then  you  may  come  to  me, 
and  I  will  explain  to  you  why  it  moves  that 
way." 

"  Well,"  said  Rollo,  "  come,  Nathan,  let  us 
go.  First  we  will  hold  it  at  the  key-hole 
of  the  door." 

Rollo  held  the  end  of  the  thread  up  oppo- 
site to  the  door,  in  such  a  way,  that  the  tuft 
was  exactly  before  the  key-hole.  The  tuft 
was  at  once  blown  out  into  the  room. 

""O,  see,  Nathan,  how  it  blows  out.  The 
air  is  coming  in  through  the  key-hole." 

"Yes,"  said  his  mother;  "when  there  is 
a  fire  in  the  room,  and  none  in  the  entry, 


113 


then  the  cold  air  in  the  entry  runs  down 
through  the  key-hole  into  the  room." 

"  It  don't  run  down,  mother,"  said  Rollo  ; 
"it  blows  right  in  straight." 

"  Perhaps  I  ought  to  have  said  it  spouts 
in,"  said  his  mother,  "just  as  the  water  did 
from  the  hole  in  your  dam.  And,  now,"  she 
continued,  "  come  and  hold  the  tuft  near  the 
chimney." 

Rollo  did  so ;  and  he  found  that  it  was 
carried  in,  proving,  as  their  father  had  showed 
them  before,  that  the  heavy,  cold  air,  pressing 
into  the  room,  crowded  the  warm,  light  air 
up  the  chimney. 

"  Now,  should  you  think,"  said  their  mother, 
"  that  the  cold  air  could  come  in  through  the 
key-hole,  as  fast  as  it  goes  up  the  chimney  ?  " 

Both  Rollo  and  Nathan  thought  that  it 
could  not. 

"  Then  go  all  around  the  room,"  said  she, 
"  and  see  if  you  can  find  any  other  place, 
where  it  comes  in.  For  it  is  plain,  you  see, 
that  the  light  air  cannot  be  driven  up  chim- 
ney any  faster  than  cold  and  heavy  air  comes 
in  to  drive  it  up  and  take  its  place." 

So  Rollo  and  Nathan  went  around  the 
room,  holding  their  tuft  at  ail  the  places  they 
e*  10* 


114  AIR. 

could  find,  where  they  supposed  there  could 
be  openings  for  the  cold  air  to  press  in. 
They  found  currents  coming  in  around  the 
windows,  and  by  the  hinges  of  the  doors; 
and  at  length  Rollo  said,  he  meant  to  open 
the  window  a  little  way,  and  see  if  the  cold 
air  from  out  of  doors  would  not  press  in  there 
too.  He  did  so,  and  the  tuft  was  blown  in 
very  far,  showing  that  the  cold  air  from  out 
of  doors  pressed  in  very  strongly. 

"  Now,  if  all  these  openings  were  to  be 
stopped,"  said  their  mother,  "  then  no  cold  air 
could  crowd  into  the  room ;  and  of  course 
the  hot  air  could  not  be  buoyed  up  into  the 
chimney,  and  a  great  deal  of  the  hot  air  and 
smoke  would  come  into  the  room.  This 
very  often  happens  when  houses  are  first 
built,  and  the  rooms  are  very  tight. 

"  But  now,  Rollo,"  she  continued,  "  suppose 
that  the  door  was  opened  wide ;  then  should 
not  you  think  that  more  cold  and  heavy  air 
would  press  in,  than  could  go  up  the  chim- 
ney ?  " 

"  Yes,  mother,  a  great  deal  more,"  said 
Rollo. 

"  Try  it,"  said  his  mother. 

So  Rollo  opened  the  door,  and  held   his 


11? 


tuft  in  the  passage-way ;  and  he  found  that 
the  air  was  pressing  in  very  strongly  through 
the  open  space.  Wherever  he  held  it,  it  was 
blown  into  the  room  a  great  deal,  showing 
that  the  heavy  air  pressed  in,  in  a  torrent. 

"Now,  as  much  warm  air  must  go  out," 
said  she,  "  as  there  is  cold  air  coming  in  ;  but 
I  don't  believe  that  you  and  Rollo  can  find 
out  where  it  goes  out." 

Rollo  looked  all  around  the  room,  but  he 
could  not  see  any  opening,  except  the  chim- 
ney and  the  door,  and  the  little  crevices, 
which  he  had  observed  about  the  finishing 
of  the  room.  He  said  he  could  not  find  any 
place. 

His  mother  then  told  him  to  hold  his  tuft 
down  near  the  bottom  of  the  door-way.  He 
did  so,  and  found  that  the  current  of  air  was 
there  very  strong.  The  tuft  swung  into  the 
room  very  far. 

"  Now  hold  it  up  a  little  higher,"  said  his 
mother. 

Rollo  obeyed,  and  he  found  that  it  was 
still  pressed  in,  but  not  so  hard. 

"  Higher,"  said  his  mother. 

Rollo  raised  it  as  high  as  he  could  reach. 
The  thread  was  of  such  a  length,  that  the 


116  AIR. 

tuft  hung  about  opposite  to  his  shoulder. 
The  tuft  was  still  pressed  in,  but  not  nearly 
as  far  as  before. 

"  So  you  see,"  said  his  mother,  "  that  the 
air  pours  in  the  fastest  at  the  lowest  point, 
where  the  weight  and  pressure  of  the  aii 
above  it  are  the  greatest ;  just  as,  in  your 
dam,  the  water  from  the  lowest  holes  spout- 
ed out  the  farthest." 

"  Yes,"  said  Rollo,  "  it  is  very  much  like 
that." 

"  Now,"  continued  his  mother,  "  you  see 
that  a  great  deal  of  air  comes  in,  and  if  you 
look  up  chimney,  you  will  see  that  there  is 
scarcely  room  for  so  much  to  go  up  there ; 
—  and  yet  just  as  much  must  go  out  as 
comes  in. 

"  Get  the  step-ladder,"  said  his  mother, 
"and  stand  up  upon  it,  and  so  hold  your 
tuft  in  the  upper  part  of  the  door-way." 

There  was  in  the  china  closet  a  small 
piece  of  furniture,  very  convenient  about  a 
house,  called  a  step-ladder.  It  consisted  of 
two  wooden  steps,  and  was  made  and  kept 
there  to  stand  upon,  in  order  to  reach  the 
high  shelves.  Rollo  brought  out  the  step- 
ladder,  and  placed  it  in  the  door-way,  and 


LI7 


then  ascended  it.  From  the  top  he  could 
reach  nearly  to  the  top  of  the  door ;  but  then, 
as  his  tuft  was  at  the  end  of  the  thread,  it 
hung  down,  of  course,  some  little  distance 
below  his  head. 

"  Why,  mother,"  said  Rotlo,  "  it  goes  out." 
"Yes,"  repeated  Nathan,  "it  goes  out." 
In  fact,  Rollo  found  that  the  tuft,  instead 
of  swinging  into  the  room,  was  carried  put 
towards  the  entry. 

"You  have  found  out,  then,"  said  his 
mother,  "  where  the  hot  air  of  the  room  goes 
to,  to  make  room  for  the  cold  air,  that  comes 
in  from  the  entry." 

"  Yes,  out  into  the  entry,"  said  Rollo. 
"  Through  the  upper  part  of  the  door," 
said  his  mother.  "  Suppose  the  entry  were 
full  of  water,  and  the  parlor  full  of  air,  and 
the  door  was  shut,  and  the  door  and  the  walls 
were  water-tight.  Now,  if  you  were  to  open 
the  door,  you  see  that  the  water,  being  heavier,, 
would  flow  in,  through  the  lower  part  of  the 
door-way,  into  the  parlor,  and  the  air  from 
the  parlor  would  flow  out,  through  the  upper 
part  of  the  door- way,  into  the  entry-  The 
water  would  settle  down  in  the  entry,  until 
it  was  level  in  both  rooms,  and  then  the  lower 


118 


parts  of  both  rooms  would  be  filled  with 
water,  and  the  upper  parts  with  air." 

"  Yes,  mother,"  said  Rollo. 

"  And  it  is  just  so  with  warm  and  cold  air. 
If  the  parlor  is  filled  with  warm  air,  made 
so  by  the  fire,  and  the  entry  with  cold  air, 
and  you  open  the  door,  then  the  cold  air, 
being  heavier,  will  sink  down,  and  spread 
over  the  floor  of  both  rooms ;  and  the  warm 
air,  being  light,  will  spread  around  over  the 
upper  parts  of  both  rooms ;  and  this  will 
make  a  current  of  air,  in  at  the  bottom  of 
the  door-way,  and  out  at  the  top. 

"  Now,"  continued  his  mother,  "  let  me 
recapitulate  what  I  have  taught  you." 

"  What  do  you  mean  by  recapitulating 
it  ?  "  said  Nathan. 

"  Why,  tell  you  the  substance  of  it,  so  that 
you  3an  write  it  down  easier." 

"  O,  I  can  write  it  now,"  said  Rollo ;  "  I 
remember  it  all." 

"  Can  you  remember  it,  Nathan  ?  "  said 
his  mother. 

"Perhaps  I  can  remember  some  of  it." 
said  Nathan. 

So  Rollo  and  Nathan  went  out  into 
another  room,  where  Rollo  kept  his  desk. 


TASKS.  119 

and  they  remained  there  half  an  hour. 
When  they  returned,  they  brought  theii 
mother  two  papers. 

Their  mother  opened  the  largest  paper, 
and  read  as  follows :  — 

"  We  took  a  tuft  of  down,  tied  to  a  thread, 
and  held  it  in  the  cracks  and  places  that  the 
air  came  in  at,  to  see  which  way  it  went. 
We  held  it  at  the  window,  and  it  blew  in 
very  strong.  At  the  bottom  of  the  door,  it 
blew  in  very  strong  too  j  but  at  the  top,  it 
blew  out,  into  the  entry.  So,  when  the  entry 
is  full  of  cold  air,  and  this  room  full  of  warm, 
the  cold  air  will  press  in  and  drive  out  soms 
of  the  warm  air,  into  the  entry. 

HOLLO." 

The  other  paper  was  also  in  Hollo's  hand- 
writing, and  was  as  follows :  — 

"  If  the  entry  was  full  of  water,  and  the 
parlor  full  of  air,  and  the  walls  were  water- 
tight, and  you  were  to  open  the  door  be- 
tween the  two  rooms,  the  water  would  flow 
into  the  parlor  down  below,  and  the  air 


120  AIR. 

would  flow  into  the  entry  up  above.     We 
tried  it  with  a  tuft. 

NATHAN." 


QUE  STIC   NS. 

Why  were  Rollo  and  Nathan  at  first  glad  to  see  the  rain  > 
What  did  their  mother  say  to  herself  on  the  second  day, 
when  she  observed  their  weary  and  listless  appearance.' 
What  did  she  at  first  direat  them  to  do?  How  did  she 
prepare  the  downy  tuft  ?  What  experiments  did  they 
perform  wiih  it  ?  Where  did  they  find  that  the  air  came 
in  which  crowded  the  warm  air  up  the  chimney  ?  What 
experiments  did  they  perform  when  the  door  was  opened  ? 
Which  way  did  they  find  that  the  current  of  air  was  setting 
at  the  lower  part  of  the  door-way?  Which  way  did  the 
current  set  at  the  upper  part  of  the  door-way  ?  What  did 
Rollo  write  in  his  exercise  ?  What  was  written  in  Na- 
than's 


121 


CHAPTER    IX. 
BURNING. 

AFTER  the  snow  had  all  gone  off,  and  the 
ground  was  dry,  Jonas  piled  up  a  heap  of 
stumps,  roots,  and  decayed  logs,  in  a  field, 
not  far  from  the  brook,  ahd  one  sunny  after- 
noon he  and  Hollo  went  down  to  set  the 
heaps  on  fire. 

Jonas  set  one  on  fire,  and  then  he  told 
Hollo  that  he  might  set  another  on  fire. 
After  this,  Jonas  employed  himself  in  gather- 
ing up  sticks,  bushes,  roots,  and  other  such 
things  that  lay  scattered  about  the  field,  and 
putting  them  upon  the  fires,  while  Rollo 
amused  himself  in  any  way  he  pleased. 

After  a  time,  Rollo  found,  on  the  margin 
of  the  field,  near  the  edge  of  a  wood,  an  old 
stump,  taller  than  he  was,  much  decayed. 
There  was  a  hole  in  the  top.  Rollo  climbed 
up  so  that  he  could  put  a  stick  in,  and  run 
it  down,  to  see  how  far  down  the  hole  ex- 

/  11 


tended.  He  found  that  it  extended  down 
very  near  to  the  bottom. 

Then  Rollo  called  out  to  Jonas,  with  a 
loud  voice,  saying,  — 

"Jonas,  I  have  found  a  hoilow  stump 
here.  It  is  hollow  away  down  to  the  bottom. 
May  I  build  a  fire  in  it  ?  " 

"Yes,"  said  Jonas,  "  if  you  can." 

Rollo  accordingly  went  to  the  nearest  fire, 
and  got  a  quantity  of  birch  bark,  which  he 
had  collected  there  to  aid  him  in  kindling 
his  fires.  He  lighted  one  piece,  and  put  it 
upon  the  end  of  a  stick,  and  carried  it  to  the 
stump,  with  the  rest  of  the  birch  bark  in  the 
other  hand. 

Rollo  then  spent  some  time  in  fruitless 
attempts  to  make  some  lighted  birch  bark  go 
down  into  the  stump,  and  burn  there.  He 
succeeded  very  well  in  getting  pieces  com- 
pletely on  fire  ;  but,  after  they  were  dropped 
into  the  hole,  they  would  not  burn.  Rollo 
could  not  think  what  the  reason  could  be. 

At  last  he  called  Jonas  to  come  and  help 
him  set  the  stump  on  fire. 

Jonas  said  that  he  did  not  think  that  it 
could  be  set  on  fire. 


BURNING.  125 

"  Why  not  ?  "  said  Rollo. 

"Because,"  said  Jonas,  "it  is  so  wet." 

"Yes,  but,  Jonas,"  replied  Rollo,  "your 
brush  heaps  burn,  and  why  should  not  this 
stump  ? " 

"  Because,"  said  Jonas,  "  the  stump  is 
more  solid,  and  the  water  soaks  into  it  more 
in  the  winter  and  early  in  the  spring  ;  and  it 
takes  it  much  longer  to  dry,  than  it  does 
brush  and  small  roots,  which  lie  operi  and 
exposed  to  the  air." 

"  Well,  then,"  replied  Rollo,  "  why  does 
not  my  birch  bark  burn  ?  that  is  dry ;  but  as 
soon  as  I  drop  it  down  into  the  stump,  it 
goes  out." 

Jonas  looked  into  the  stump,  and  down 
around  the  bottom  of  it,  and  said,  — 

"  Because  there  is  no  air." 

"No  air?"  repeated  Rollo. 

"  No,"  replied  Jonas ;  "  it  is  all  close  and 
solid  around;  the  air  cannot  get  in." 

"It  can  get  in  at  the  top,"  said  Rollo. 

Jonas  made  no  reply  to  this  remark,  but 
walked  away  a  few  steps,  to  a  place  where 
he  had  put  down  his  axe ;  he  took  up  the 
axe,  and  brought  it  to  the  stump.  He 
immediately  began  to  cut  into  it,  at  the 
11* 


126 


bottom,  as  if  it  were  a  tree  which  he  \vas 
going  to  fell. 

"O  Jonas,"  said  Rollo,  "don't  cut  it 
down." 

"  I  am  not  going  to  cut  it  down,"  said 
Jonas :  "  I  am  only  going  to  cut  a  hole  into  it." 

"What  for?"  asked  Rollo. 

"  To  let  the  air  in,"  replied  Jonas. 

Jonas  continued  to  cut  into  the  side  of  the 
stump,  near  the  ground,  until  he  perceived 
that  the  edge  of  his  axe  went  through  into 
the  hollow  part.  Then  he  cleared  away  the 
chips  a  little,  and  showed  Rollo  that  there 
was  an  opening  for  the  air. 

"  Now,"  said  he,  "  I  presume  you  will  be 
able  to  make  sticks  and  birch  bark  burn  in 
the  stump,  though  you  can't  make  the  stump 
itself  burn  very  well." 

Rollo  now  dropped  a  blazing  piece  of  birch 
bark  into  the  stump,  and,  to  his  great  joy, 
he  found  that  it  continued  blazing,  after  it 
reached  the  bottom.  He  then  dropped  in 
another  piece  upon  it,  which  took  fire.  He 
then  gathered  some  dry  sticks,  and  put  in ; 
and.  finding  that  the  flame  was  increasing,  he 
proceeded  to  gather  all  the  dry  and  combus- 
tible matter,  which  he  could  find  around,  and 


127 


put  them  in,  so  that  in  a  short  time  he  had 
a  fine  blaze,  a  foot  above  the  top  of  the 
stump ;  and  the  inside  of  the  stump  itself 
seemed  to  be  in  flames. 

"  Jonas,"  said  Hollo,  "it  does  burn." 

"  Does  it  ? "  said  Jonas ;  "I  am  glad  to 
hear  it." 

"  But  you  said  the  stump  would  not  burn." 

"You  ought  to  wait  until  it  is  all  bunt 
up,  before  you  triumph  over  me." 

"  Why,  Jonas,"  said  Hollo,  "  I  didn't  mean 
to  triumph  over  you  ;  but  why  would  not  the 
fire  burn  before  you  cut  the  hole  through  ? " 

"  Because,"  replied  Jonas,  "  there  was  not 
air  enough." 

"  There  was  air  in  the  stump,"  said  Rollo. 

"Yes,"  replied  Jonas,  "but  all  the  life  of 
it  was  consumed  by  the  first  piece  of  birch 
bark  which  you  put  in." 

"  The  life  of  it  ?  "  said  Rollo. 

"  Yes,"  replied  Jonas ;  "  what  do  you 
suppose  it  is,  that  makes  anything  burn  ?  " 

"  Why,  it  burns  itself,"  said  Rollo. 

"  No,"  answered  Jonas ;  "  the  air  makes  it 
burn :  it  must  have  good  air  around  it,  or 
else  it  won't  burn.  There  is  something  in 
the  air  which  I  call  the  life  of  it ;  this  makes 


128 


the  fire  burn.  But  when  this  is  all  gone, 
then  that  air  will  not  make  fire  burn  any- 
longer.  It  will  only  burn  in  good  fresh  air. 
which  has  got  the  life  in  it." 

"  I  thought  fire  would  burn  in  any  kind 
of  air,"  said  Rollo. 

"  No,"  replied  Jonas  ;  "  you  can  see  if  you 
stop  up  the  hole  I  made  here." 

Jonas  then  took  a  piece  of  turf  from  the 
field,  and  put  it  before  the  hole,  and  crowded 
it  in  hard  with  the  heel  of  his  boot.  Rollo 
observed  that  the  fire  was  almost  immedi- 
ately deadened. 

"Now,"  continued  Jonas,  "light  a  small 
piece  of  birch  bark,  and  put  it  in." 

Jonas  helped  Rollo  fasten  a  small  piece  of 
bark  upon  the  end  of  a  stick,  and  then  Rollo 
set  it  on  fire,  and  held  it  down  a  little  way 
into  the  stump.  It  burned  very  feebly. 

"  See,"  said  Jonas,  "  how  quick  it  is 
stifled." 

"  Yes,"  replied  Rollo,  "  it  goes  out  almost 
directly." 

"  You  see,"  said  Jonas,  "  that  the  fire 
already  in  the  stump  consumes  all  the  good- 
tiess  of  the  air ;  and  I  stopped  up  the  hole, 
so  that  no  fresh  air  can  come  in." 


BURNING.  129 

"  Why  doesn't  it  go  in  at  the  top  ? "  said 
Hollo. 

"  It  does  a  little,"  said  Jonas,  "  but  not 
much,  because  the  hollow  of  the  stump  is 
already  full  of  bad  air,  and  there  is  nothing  to 
make  a  current.  When  there  is  an  opening 
below,  then  there  is  a  current  up  through." 

"  Yes,"  said  Hollo,  "it  is  just  like  a  chim- 
ney." 

"  Yes,"  replied  Jonas,  "  the  stump  is  the 
chimney,  and  the  hole  is  the  fireplace." 

"  And  the  air  in  the  stump,"  said  Hollo, 
"gets  hot,  and  so  the  cold  air  all  around  is 
heavier,  and  so  it  crowds  down  under  it,  and 
buoys  the  hot  air  up  out  of  the  stump.  My 
father  explained  it  all  to  Nathan  and  me." 

Rollo  then  wanted  to  open  the  hole  again, 
to  see  if  the  effect  would  be  as  he  had  de- 
scribed. 

Then  Jonas  pulled  away  the  turf  from  the 
hole  at  the  bottom  of  the  stump,  and  Rollo 
observed  that  the  fire  brightened  up  imme- 
diately. 

He  then  held  a  smoking  brand  near  the 
hole,  and  he  saw  that  the  smoke  was  carried 
in,  in  a  very  strong  current,  by  the  cool  air, 
which  was  pressing  into  the  hole. 


130  AIR. 

"  Yes,"  said  Rollo,  "  it  operates  just  like  a 
fireplace." 

"So  you  see,"  continued  Jonas,  "that 
whenever  you  build  a  fire,  you  must  see  to 
it,  that  there  is  an  opening  for  air  to  come  up 
from  underneath  it.  And  it  must  be  good 
fresh  air  too." 

"  What  is  it  in  the  air,  which  makes  the 
fire  burn  ?  "  said  Rollo. 

"I  don't  know  what  the  name  of  it  is," 
said  Jonas ;  "  it  is  some  part  of  the  air,  which 
goes  into  the  fire,  and  is  all  consumed,  and 
then  the  rest  of  the  air  is  good  for  nothing." 

"  Isn't  it  good  for  anything  at  all  ?  "  asked 
Rollo. 

"  I  don't  know,"  said  Jonas,  "  how  that  is ; 
only  I  know  that  it  isn't  good  for  anything 
for  fires.  It  stifles  them." 

"  I  should  like  to  know  what  the  name  of 
that  part  of  the  air  is,  which  is  good  for  fires," 
said  Rollo. 

"  I  knew  once,"  said  Jonas,  "  but  it  was  a 
hard  word,  and  I  have  forgotten  it." 

"I  mean  to  ask  my  father,"  said  Rollo. 

Jonas  then  went  on  with  his  work,  gather- 
ing up  everything  that  he  could  find  around 
the  field,  to  put  upon  the  fires.  Rollo  amused 


131 


himself  by  putting  large  rolls  of  birch  bark 
around  the  end  of  a  stick,  and  then,  after  set- 
ting them  on  fire,  holding  them  over  the 
fires,  which  Jonas  was  making,  to  see  how 
soon  the  flame  was  extinguished :  then  he 
would  draw  them  away,  and  see  them  revive 
and  blaze  up  again  in  the  open  air.  At  last, 
he  called  out  to  Jonas,  once  more. 

"  Jonas,"  said  he,  "I  have  found  out  what 
makes  the  blaze  go  out.  It  is  the  smoke. 
I  don't  believe  but  that  it  is  the  smoke." 

"  No,"  replied  Jonas,  "  it  is  not  the  smoke. 
I  can  prove  that  it  is  not." 

So  Jonas  came  up  to  the  fire  where  Rollo 
was  standing,  and  pointed  out  to  Rollo  a 
place,  over  a  hot  part  of  it,  where  there  was 
no  smoke,  because  the  fire  under  it  burned 
clear,  being  nearly  reduced  to  coals.  He 
told  Rollo  to  hold  his  blazing  bark  there. 
Rollo  did  so,  and  found  that  it  was  extin- 
guished at  once,  and  as  completely,  as  it  had 
been  before,  when  he  had  held  it  in  a  dense 
smoke. 

"Yes,"  said  Rollo,  "it  isn't  the  smoke. 
But  perhaps  it  is  because  it  is  so  hot." 

"  No,"  said  Jonas,  "  it  isn't  that.  It  is  a 
difference  in  the  air.  They  sometimes  collect 


132  AT*. 

different  kinds  of  air  in  glass  jars,  and  then  let 
a  candle  down  in,  and  see  whether  it  will  go 
out." 

"  And  will  it  go  out  ?  "  said  Hollo. 

"  That  depends  upon  what  kind  of  air  it 
is,"  said  Jonas.  "  They  all  look  clear,  just 
as  if  there  was  nothing  in  the  jars ;  but  when 
you  let  a  candle  down  in,  in  some  it  burns 
just  the  same  as  before ;  in  some  it  burns 
brighter ;  and  in  some  it  goes  out." 

"  In  what  kinds  does  it  go  out  ?  "  asked 
Rollo. 

"  I  only  know  of  one  kind,"  said  Jonas, 
"and  that  is  a  kind  that  comes  of  itself  in 
mines,  and  wells,  and  other  places." 

"  What  is  the  name  of  it  ?  "  asked  Rollo. 

"  Why,  the  people  in  the  mines  call  it 
choke  damp ;  but  1  believe  it  has  got  another 
name  besides." 

"  What  do  they  call  it  choke  damp  for  ?  " 
said  Rollo. 

"  Because,"  said  Jonas,  "  if  the  miners  get 
into  it  and  breathe  it,  it  kills  them.  It  is  not 
any  better  to  breathe  than  it  is  to  make  fires 
burn." 

"  I  wish  I  could  see  some  choke  damp/' 
said  Rollo. 


BURNING.  133 

"  O,  you  can't  see  it  at  all,"  said  Jonas,  "  if 
it  was  right  before  you,  any  more  than  you 
can  see  common  air.  If  a  well  or  a  mine  is 
is  full  of  it,  they  cannot  find  it  out  by  look- 
ing down." 

"How  do  they  find  it  out?  "  said  Rollo. 

"  Why,  they  let  a  candle  down,"  replied 
Jonas. 

"  And  will  the  candle  go  out  ?  "  asked 
Rollo. 

"Yes,"  said  Jonas,  "if  there  is  choke 
damp  in  the  well.  Sometimes  they  make  a 
little  of  it  in  a  tumbler  or  a  jar  upon  the 
table,  and  so  let  a  little  flame  down  into  it, 
and  it  goes  out  immediately." 

"  I  wish  we  could  make  some,"  said 
Rollo.  "  Do  you  know  how  they  make  it  ? " 

"No,"  said  Jonas;  "but  I  believe  it  is 
pretty  easy  to  do  it,  if  we  only  knew  how." 

"  I  will  ask  my  father,"  said  Rollo ;  "  per- 
haps he  will  know." 

This  conversation  took  place  when  Jonas 
and  Rollo  were  about  the  fires ;  but  now  the 
fires  had  pretty  nearly  burnt  out,  and  they 
prepared  to  go  home. 

That  evening,  just  about  sunset,  Rollo 
went  out  behind  the  house,  and  found  Jonas 
12 


J34  ,  AIR. 

raking  off  the  yard.  The  spring  was  fasi 
coming  on,  and  the  grass  was  beginning  to 
look  a  little  green ;  and  Jonas  said  he  wanted 
to  get  off  all  the  sticks,  chips,  and  straws,  so 
that  the  yard  would  present  a  surface  of 
smooth  and  uniform  green.  Rollo  told  him 
that  he  had  found  out  how  to  make  choke 
damp. 

"  Did  your  father  tell  you  ?  "  said  Jonas. 

"No,"  replied  Rollo. 

"  Who  did  tell  you,  then  ?  "  said  Jonas. 

"  Guess,"  answered  Rollo. 

"Your  mother,"  said  Jonas. 

"No,"  answered  Rollo. 

"  Then  I  can't  tell,"  said  Jonas. 

"It  was  Miss  Mary,"  replied  Rollo.  "I 
met  her  in  the  road  to-day,  and  I  asked  her." 

"  And  how  is  it  ?  "  asked  Jonas. 

"  Why,  we  make  it  with  chalk  and  vine- 
gar," said  Rollo.  "We  pound  up  a  little 
chalk,  and  put  it  in  the  bottom  of  a  tumbler. 
Then  we  pour  some  vinegar  over  it.  The 
vinegar  takes  the  choke  damp  out  of  the 
chalk,  and  Miss  Mary  says  it  will  come  up 
in  little  bubbles.  She  says  we  can  lay 
a  paper  over  the  top  loosely,  —  she  said 
loosely,  but  I  think  it  ought  to  be  tight." 


BURNING.  135 

"Why?  "asked  Jonas. 

"So  as  to  keep  the  choke  damp  from 
coming  out,"  replied  Rollo. 

"  No,"  said  Jonas.  "  I  understand  why 
she  said  you  must  put  it  on  loosely ;  that's 
to  let  the  common  air  out." 

"  What  common  air  ?  "  said  Hello. 

"  Why,  the  air  that  was  in  the  tumbler 
before,"  replied  Jonas.  "  You  see  that,  as 
fast  as  the  choke  damp  comes  up,  it  drives 
the  common  air  out  of  the  top  of  the  tum- 
bler ;  and  so  you  must  put  the  paper  on  loose- 
ly, and  let  it  go  out." 

That  evening  Jonas  and  Rollo  tried  the 
experiment.  First  they  put  about  two  tea- 
spoonfuls  of  chalk  into  the  tumbler.  Then 
they  poured  in  the  vinegar.  It  immediately 
began  to  foam. 

"Ah,"   said   Rollo,  "that's  the   efferves- 


cence. 


"The  what?"  said  Dorothy;  for  they 
were  making  this  experiment  upon  the 
kitchen  table,  and  Dorothy  was  standing  by, 
looking  on  with  great  interest. 

"The  effervescence,"  said  Rollo.  "Miss 
Mary  said  there  would  be  an  effervescence, 
which  would  be  occasioned  by  the  little 


136  AIR. 

bubbles  01  choke  damp,  coming  up  from  the 
chalk." 

"  Poh !  "  said  Dorothy ;  "  it's  nothing  but 
a  little  frothing." 

"  It  isn't  frothing,"  said  Rollo,  very  se- 
riously ;  "  it  isn't  frothing,  it  is  effervescence 
Don't  you  think  Miss  Mary  knows  ?  " 

"  Jonas,"  said  Rollo  again  after  a  short 
pause,  "  how  many  of  these  little  bubbles 
will  it  take,  do  you  think,  to  fill  the  tumbler 
full  of  choke  damp  ?  " 

"  I  don't  know,"  replied  Jonas  ;  "  we  will 
wait  a  little  while,  and  then  try  it." 

"There,  now,  Jonas,"  said  Rollo,  "we 
have  not  got  any  candle." 

"  O,  I  will  roll  Up  a  piece  of  paper,  and 
set  the  end  on  fire,  and  then  dip  it  down 
into  the  tumbler,  and  that  will  do  just  as 
well." 

"What  are  you  going  to  do  that  for?" 
said  Dorothy. 

"  Why,  to  see  it  go  out,"  said  Rollo. 

"  It  won't  go  out,  unless  you  put  it  away 
down  into  the  vinegar,"  said  Dorothy. 

"  Yes  it  will,"  said  Rollo  ;  "  we  are  only 
going  to  dip  it  down  a  little  way,  just  into 
the  choke  damp,  and  it  will  gc  out." 


137 


"  It  won't  go  out,  child,"  said  Dorothy. 
"  There's  nothing  to  put  it  out." 

"Well,  you'll  see.  Won't  it  go  out, 
Jonas  ?  " 

"  I  don't  know,"  said  Jonas. 

"  Don't  know  ?  "  said  Rollo.  "  Why,  you 
told  me  that  choke  damp  would  put  out  a 
blaze." 

"  Yes,"  said  Jonas,  "  I  am  sure  of  that  ; 
but  there  are  a  great  many  ways  of  failing  in 
trying  experiments." 

"Well,"  said  Rollo,  "that  may  be;  but 
this  will  not  fail,  I  know,  for  I  can  see  the 
little  bubbles  of  choke  damp  coming  up. 
There  are  millions  of  them." 

By  this  time  Jonas  thought  that  the  tum- 
bler was  filled  with  the  gas,  which  was  rising 
from  the  chalk  and  vinegar.  So  he  rolled  up 
a  piece  of  paper,  and  set  the  end  on  fire,  and, 
when  it  was  well  burning,  he  plunged  the 
end  of  it  into  the  tumbler.  To  Rollo 's  great 
disappointment  and  mortification,  it  continued 
to  burn  about  as  much  as  ever.  The  flame 
crept  rapidly  up  the  paper,  and  Jonas  had 
soon  to  run  with  it  across  the  floor  and  throw 
it  into  the  fire,  to  avoid  burning  his  fingers. 
Dorothy  laughed  aloud ;  Jonas  smiled ;  and 

/*  12* 


138 


as  for  Rollo,  he  looked  disappointed  and 
vexed,  and  appeared  to  be  overwhelmed  with 
chagrin. 

Dorothy  continued  to  laugh  at  them,  while 
Jonas  went  to  the  pump  and  washed  out  the 
nimbler.  At  length  she  said,  - — 

"  But  come,  Rollo,  don't  be  so  disconsolate. 
You  look  as  if  you  had  swallowed  all  the 
choke  damp." 

"  Yes,  Rollo,"  said  Jonas,  "  we  must  keep 
good-natured,  even  if  our  experiments  do 
fail." 

"  Well,"  said  Rollo,  "  I  mean  to  ask  Miss 
Mary  again,  and  then  we  can  do  it,  I  know." 

Rollo  accordingly  went,  the  next  day,  to 
ask  Miss  Mary  about  the  cause  of  the  failure. 
Miss  Mary  said  that  she  could  not  think  of 
any  thing  which  was  likely  to  be  the  cause, 
unless  it  was  that  they  put  too  large  a  flame 
into  the  tumbler. 

"Well,"  replied  Rollo,  "and  what  harm 
would  that  do  ?  Won't  the  choke  damp  put 
out  a  large  flame  ?  " 

"Yes,"  replied  Miss  Mary,  "if  it  only 
fairly  surrounds  and  covers  it ;  but,  thent  if 
you  put  a  large  flame  into  a  tumbler,  it  makes 


BURNING.  139 

the  first  instant,  a  great  current  of  air,  and  so 
the  choke  damp  might  be  blown  out,  and 
common  air  get  in,  and  so  keep  the  paper, 
burning.11 

"How  does  it  make  a  current  of  air?" 
asked  Rollo. 

"  Why,  the  heat  of  the  flame,  when  you 
first  put  the  paper  in,"  replied  Miss  Mary, 
"makes  the  air  that  is  above  it  lighter; 
and  the  common  air  all  around  crowds  in 
under  it,  in  buoying  it  up;  and  by  that 
means,  if  the  flame  is  too  large,  common  air 
is  carried  into  the  tumbler.  You  ought  to 
make  a  very  small  flame,  if  you  leave  the  top 
of  the  tumbler  open." 

"  How  can  we  make  a  small  flame  ? "  said 
Rollo. 

"  One  good  way,"  replied  Miss  Mary,  "  is 
to  roll  up  some  paper  into  a  very  small  roll. 
I  will  show  you  how." 

So  Miss  Mary  took  a  piece  of  paper,  and 
cut  it  into  the  proper  shape  with  her  scissors, 
and  then  rolled  it  up  into  a  long  and  very 
slender  roll ;  one  end  of  it  was  not  much 
larger  than  a  large  knitting-needle.  She  gave 
this  to  Rollo,  and  told  him  that,  if  he  tried 
the  experiment  again,  he  must  light  the  small 


140 


end,  and  it  would  make  a  flame  not  so  big  as 
a  pea. 

Rollo  explained  to  Jonas  what  Miss  Mary 
had  said,  and  they  resolved  on  attempting  the 
experiment  again  that  evening.  And  they 
did  so.  Dorothy  stood  by  watching  the  pro- 
cess, as  she  had  done  the  evening  before , 
but  Rollo  did  not  assert  so  confidently  and 
positively  what  the  result  would  be.  He 
had  learned  moderation  by  the  experience  of 
the  night  before. 

When  all  was  ready,  Jonas  lighted  the  end 
of  the  slender  roll  in  the  lamp,  and  plunged 
it  carefully  into  the  tumbler.  It  went  out 
immediately. 

"  There  !  "  said  Rollo,  clapping  his  hands, 
"  it  goes  out." 

"  Why,  it  is  only  because  the  wind  blew 
it  out." 

"No,  Dorothy,"  said  Rollo,  "there  isn't 
any  wind  in  the  tumbler." 

"  Yes,"  replied  Dorothy,  "  when  you  push 
it  down,  it  makes  a  little  wind,  just  enough 
to  blow  it  out." 

"  Get  another  tumbler,"  said  Jonas,  "  and 
et  us  see." 

So  Dorothy  brought  another  tumbler,  and 


BURNING.  141 

Jonas  put  the  burning  end  of  the  paper  down 
into  it,  with  about  as  rapid  a  motion  as  that 
with  which  he  had  put  it  before  into  the 
tumbler  he  had  at  first.  The  paper  con- 
tinued to  burn. 

"There,"  said  he  to  Dorothy,  "when  I 
put  it  down  into  common  air,  it  burns  on 
the  same  as  ever ;  so  it  can't  be  that  the  wind 
puts  it  out."  Jonas  repeated  the  experiment 
a  number  of  times;  the  effect  was  always 
the  same.  Whenever  he  put  it  into  the 
tumbler  of  common  air,  it  burned  on  without 
any  change  ;  but  whenever  he  put  it  into  the 
choke  damp,  it  immediately  went  out.  Even 
Dorothy  was  satisfied  that  there  was  a  differ- 
ence in  the  kind  of  air  contained  in  the  two 
tumblers. 

That  evening,  when  Rollo  gave  his  mother 
a  full  account  of  their  attempts,  —  describing 
particularly  their  failure  at  first,  and  their 
subsequent  successes,  —  his  mother  seemed 
much  interested.  When  he  had  finished,  she 
said, — 

"Well,  Rollo,  I  don't  see  but  that  you 
have  learned  two  lessons  in  philosophy." 

"  Two  lessons  ?  "  said  Rollo. 

"  Yes,"  replied  his  mother.     "  The  first  is, 


142 


that  fire  will  not  burn  in  choke  damp ;  and 
the  second  is,  that  it  requires  nice  attention 
and  care  to  verify  philosophical  truths  by  ex- 
periment." 

"  Yes,"  said  Rollo,  "  we  missed  the  first 
time,  just  because  we  had  too  big  a  paper." 


QUESTIONS. 

Why  did  Jonas  suppose  that  the  stump  would  not  burn  ? 
What  was  Rollo's  first  mode  of  setting  it  on  fire  ?  How 
did  it  succeed  ?  What  did  Jonas  do  with  his  axe,  when  he 
came  ?  What  was  the  object  of  this  ?  What  did  he  say 
was  necessary  to  make  fires  burn  ?  What  did  Rollo  at  first 
think  was  the  reason  why  the  bark  went  out  when  held 
over  the  fire  ?  What  did  he  next  think  was  the  reason  ? 
How  did  Jonas  say  that  different  kinds  of  airs  were  pre- 
pared ?  In  what  places  did  he  say  that  choke  damp  was 
naturally  produced?  How  did  they  attempt  to  prepare 
some  of  this  gas  ?  Did  they  succeed  in  preparing  it  ?  Did 
they  succeed  in  their  experiment  at  first '  What  was  the 
cause  of  the  failure? 


143 
CHAPTER    X. 

GRAVITATION. 

ONE  evening,  after  tea,  when  Rollo  was 
a  pretty  big  boy,  he  came  and  began  to 
climb  up  into  his  father's  lap.  When  he  had 
climbed  up,  he  took  his  place  astride  of  his 
father's  knee,  as  if  he  were  riding  a  horse. 
His  little  brother  Nathan  came  up  and  stood 
near,  wanting  to  get  up  too,  only  there  was 
not  room.  His  cousin  James  was  there,  that 
evening,  on  a  visit.  He  sat  upon  a  cricket 
before  the  fire,  and  his  mother  was  at  the 
table  doing  some  sort  of  work. 

"  O  dear  me !  "  said  Hollo's  father,  imita- 
ting the  tone  in  which  Rollo  sometimes 
uttered  that  exclamation. 

"What,  sir?"  said  Rollo. 

"  Why,  I  should  like  very  well  to  hold 
you  in  my  lap,"  said  his  father,  "  if  it  was  not 
for  the  great  mighty  earth,  down  below  us." 

"  How  ?  "  said  Rollo.  He  did  not  know 
what  his  father  meant. 


144  Ant. 

"  Why,  when  you  are  upon  my  knee,  the 
earth,  the  ponderous  earth,  pulls  you  down 
hard  and  heavy  upon  it."  So  saying,  he 
put  his  hands  upon  Rollo's  shoulders,  and 
crowded  them  down,  by  way  of  showing 
him  how  the  earth  acted  upon  him.  "  It 
pulls,"  he  continued,  "  with  a  strong  and 
steady  pull,  all  the  time ;  and  so  makes  you 
a  very  heavy  weight." 

"  Is  that  what  makes  weight  ? "  said 
Rollo. 

"  Yes,"  said  his  father.  "  So,  if  I  had  a 
monstrous  stone  to  move,  and  if  I  thought 
the  earth  would  listen  to  me,  and  let  go  its 
hold,  I  might  make  a  speech  to  it  thus :  — 

"  '  O  earth,  thou  vast  and  ponderous  ball, 
please  to  relax  thy  hold,  for  a  few  min- 
utes, upon  this  stone,  and  leave  it  free  to 
move  ;  and  then  Rollo  can  tie  a  string  to  it, 
and  move  it  easily  along  to  the  place  where 
I  want  it  to  lie  :  then  thou  mayst  seize  it 
again  with  thy  mighty  attraction,  and  hold 
it  down  as  firmly  as  thou  wilt.' " 

"  O  father  !  "  exclaimed  Rollo  ;  Nathan 
and  James  laughed,  and  Rollo's  mother 
looked  up  from  her  work  to  listen  to  this 
strange  apostrophe. 


GRAVITATION.  145 

"  It  would  seem,"  continued  his  father,  in 
a  pompous  tone,  as  if  still  addressing  the 
earth  —  "  it  would  seem,  most  mighty  planet, 
a  very  easy  thing  for  thee  to  release  this 
single  stone,  for  a  few  minutes,  from  the  grasp 
with  which  thou  boldest  all  things  down 
upon  thy  surface.  And  by  it  I  shall  gain 
much,  while  thou  wilt  lose  nothing ;  for,  if 
thou  wilt  not  willingly  give  up  the  stone,  I 
must  get  three  or  four  yoke  of  strong  oxen, 
and,  by  main  force,  pull  it  away." 

"  Is  that  what  makes  everything  heavy  ?  " 
said  Rollo. 

"  Yes,"  said  his  father,  answering  now 
in  his  natural  tone ;  "the  attraction  of  the 
earth  is  what  makes  everything  heavy,  and 
holds  it  down." 

"  And  could  we  move  a  monstrous  great 
stone,"  said  Rollo,  "as  light  as  a  feather?" 

"  No,"  said  his  father,  "  it  would  not  move 
along  quick  and  light,  like  a  feather.  You 
could  not  move  it  quick.  Suppose,  for 
instance,  you  had  two  boats,  floating  upon 
the  water,  of  the  same  size  ;  one  made  very 
light  indeed,  of  something  very  thin,  like 
paper,  and  empty ;  and  the  other  made  of 
wood,  and  loaded  with  iron  as  heavily  as  it 
8  13 


146  AIR. 

would  bear.  Now,  they  would  both  be  sup- 
ported upon  the  water,  so  that  their  weight 
would  be  neutralized ;  and  yet  they  would 
move  very  differently.  You  could  push  the 
light  one  about  easily,  anywhere,  but  the 
heavy  one  would  move  very  slowly.  You 
would  not  have  to  push  very  hard  upon  it, 
but  you  would  have  to  push  for  some  time, 
to  set  it  in  motion ;  and  then  it  would  be 
hard  to  stop  it.  This  is  called  its  inertia." 

"  Yes,"  said  Rollo,  "  it  would  go  harder 
against  the  bank." 

"  The  reason  is,"  continued  his  father, 
"  that  the  heavy  boat  contains  a  great  many 
more  particles  of  matter  than  the  light  one, 
and  they  have  all  got  to  be  put  in  motion. 
So  it  requires  greater  effort,  or  the  same 
effort  must  be  continued  a  longer  time. 

"  For  instance,  if  we  suppose  that  the 
light  boat  has  one  million  of  particles  of 
matter,  the  heavy  one  would  have,  perhaps, 
twenty  millions.  Of  course  the  effect  of  the 
pushing  has  to  be  divided  among  twenty 
times  as  many  particles,  and  of  course  will 
only  carry  them  one  twentieth  part  as  far ; 
so  that  the  bodies  that  are  now  large  and 
heavy,  would  only  move  slowly,  though 


GRAVITATION.  147 

they  would  move  easily,  if  the  attraction  of 
the  earth  were  to  cease. 

"  There  is  another  way  to  illustrate  it,"  he 
continued.  "  Suppose  there  was  a  large 
mass  of  lead,  as  big  as  a  load  of  hay,  hang- 
ing by  a  chain ;  and  also  a  great  puff  of 
feathers,  or  a  balloon  of  the  same  size,  hang- 
ing in  the  same  way.  Now,  if  they  were 
both  suspended  freely,  they  would  both 
move  easily,  for  their  weight  would  be  sup- 
ported by  the  chain;  but  the  heavy  one 
would  move  very  slowly.  Nathan  could 
move  it,  but  he  could  only  move  it  slowly 
and  a  little  way." 

"  I  should  not  think  that  he  could  move 
it  but  very  little,"  said  Hollo. 

"  No,  he  could  not ;  because  you  see  that, 
in  that  way  of  suspending  anything,  the 
moment  that  it  begins  to  move,  it  begins  to 
swing  off  and  to  rise  ;  so  that  it  cannot 
be  moved  at  all  without  being  lifted  a  little. 
And  the  more  it  is  moved,  the  higher  it  is 
lifted,  so  that  it  would  take  a  great  force  to 
move  it  far  away  from  the  centre,  where  it 
was  hanging.  But  we  can  hang  it  in  a  way 
to  avoid  that  difficulty." 

"How.  sir?  "  said  Hollo. 


148  AIR. 

Rollo  seemed  to  be  very  much  interested 
in  this  conversation.  He  had  dismounted 
from  his  father's  knee,  and  stood  by  his  side, 
listening  eagerly.  His  mother,  too,  was  pay- 
ing close  attention.  As  for  Nathan,  he  sat 
still ;  though  it  is  not  by  any  means  certain 
that  he  understood  it  very  well. 

"Let  us  suppose,"  said  his  father,  "tha 
the  mass  of  lead,  as  big  as  a  load  of  hay 
is  fastened  to  one  end  of  a  stick  of  timber.' 

"  That  would  not  be  strong  enough  to 
hold  it,"  said  Rollo. 

"  Well,  then,  to  a  beam  of  iron,  as  large  as 
a  stick  of  timber,"  rejoined  his  father. 

"O,"  said  James,  "you  could  not  get  such 
a  big  bar  of  iron." 

"  No,"  replied  his  father,  "  only  an  imagi- 
nary one ;  and  that  will  be  just  as  good  as 
any.  Now,  suppose  the  great  mass  oHead  is 
fastened  to  one  end  of  this  bar,  and  another 
one,  just  like  it,  to  the  other  end,  to  balance 
it.  Now,  suppose  that  the  lower  end  of  the 
great  chain  is  secured  around  the  middle 
of  the  iron  beam,  and  the  upper  end  to  be 
fastened  to  some  strong  support  up  in  the  air. 
Now,  we  can  move  the  mass  of  lead  without 
having  to  lift  it  at  all ;  for,  if  we  push  against 


GRAVITATION.  149 

it,  and  make  it  move,  it  will  move  round 
and  round,  without  rising  at  all,  as  it  did 
before,  when  it  was  hung  up  directly  by  the 
chain." 

Hollo's  father  then  went  on  to  explain  to 
them  that,  in  such  a  case  as  this,  the  weight 
of  the  two  masses  of  lead  would  not  prevent 
their  moving  easily,  for  they  would  exactly 
balance  each  other.  A  little  child  would  be 
able  to  move  them;  but  still  they  would 
move  exceedingly  slow  at  first,  and  it  would 
be  hard  to  stop  them,  when  they  were  in 
motion.  So,  he  said,  if  the  earth  should 
cease  to  attract  and  draw  down  any  great, 
heavy  body,  like  a  large  stone,  for  example, 
the  smallest  child  could  lift  it,  though  it 
would  come  up  slowly,  just  as  a  very  heavy 
body  would  move,  if  it  was  suspended  by 
a  string,  or  was  afloat  upon  the  water. 

"And  so,"  said  Rollo,  "if  the  earth 
should  not  attract  us,  could  we  push  our- 
selves right  up  off  from  the  ground  ? " 

"Yes,"  said  his  father,  "most  undoubt- 
edly." 

•'  What,  and  go  about  anywhere  in  the 
air  ?  " 

"  Certainly." 

13* 


150  AIR. 

Rollo  began  to  laugh  aloud  at  this  idea, 
and  looked  very  much  interested  and  plnased. 

"  O,  then  I  wish  there  was  no  gravita- 
tion," said  Rollo  ;  "  I  do,  really." 

"  But,  then,"  continued  his  father,  "  if  you 
should  get  up  into  the  air,  you  could  not  get 
down  again." 

"  Why  not  ?  "  said  Nathan,  beginning  to 
look  a  little  concerned. 

"  Unless,"  said  his  father,  "you  had  some- 
thing above  you,  to  push  against,  so  as  to 
push  yourselves  down.  You  would  be  just 
like  a  boy  in  a  boat,  off  from  the  shore,  and 
without  any  paddle  or  pole.  He  could  not 
get  back  again." 

"  We  might  tie  a  rope  to  something," 
said  James,  "  before  we  went  up,  and  so  pull 
ourselves  down." 

"Yes,  that  yon  might  do." 

"And  could  not  we  flap  our  hands,  like  a 
bird,  and  so  fly  a  little  ?  " 

"  Perhaps  you  could,"  said  his  father. 

Here  the  children  all  began  to  flap  their 
hands,  like  young  birds  trying  to  fly ;  and 
Rollo  said  again,  he  wished,  with  all  his  heart, 
there  was  no  gravitation;  "for  then,"  said 
he,  "  we  should  have  strength  enough  to  fly." 


GRAVITATION.  151 

"  That  would  lead  to  serious  consequences,'" 
said  his  father. 

"  What  consequences?  "  said  James. 

"  Much  more  serious  than  you  would 
suppose." 

"  Tell  us  what  they  would  be,  uncle," 
said  James. 

"  O,  I  know,"  said  Rollo  ;  "  you  could  not 
stand  up  straight  without  gravitation." 

"  O,  we  could,  couldn't  we,  father  ?  "  said 
Nathan. 

"  What  makes  you  think,  Rollo,"  said  his 
father,  without  replying  to  James's  question 
—  "  what  makes  you  think  that  we  could  not 
stand  up  straight  without  gravitation  ?  " 

"  Why,  you  see,"  said  Rollo.  —  Here  he 
paused,  and  looked  confused,  and  did  not 
know  what  to  say.  He  had  an  indistinct 
recollection  of  having  read  something  about 
it  in  some  book ;  but  he  could  not  tell  what. 

"I  don't  see  what  should  prevent  any 
body's  standing  up  straight,  if  the  attraction 
of  the  earth  should  cease  ;  in  fact,  if  it  made 
any  difference,  it  would  be  rather  easier  to 
stand  up  straight." 

Here  Rollo  looked  rather  foolish,  but  he 
did  not  reply.  The  truth  is,  like  almost  all 


152 


other  children,  who  take  an  interest  in 
reading,  he  was  sometimes  a  little  vain  of 
his  knowledge ;  and  in  this  case,  instead 
of  listening  attentively,  and  endeavoring  to 
learn  something  new  from  his  father's  expla- 
nations, he  seems  to  have  thought  it  a  good 
plan  for  him  to  help  him  elucidate  the  sub- 
ject to  James  and  Nathan.  He  exchanged 
the  character  of  learner  for  teacher  too  soon. 

"  Well,  uncle,"  said  James,  "  what  would 
be  the  consequence  if  gravitation  should 
cease  ? " 

"  Why,  in  the  first  place,"  said  Hollo's  fa- 
ther, "  all  the  streams  in  the  world  would 
stop  running." 

"  The  streams  !  "  said  Hollo,  astonished. 

"Yes,"  said  his  father,  "every  river, 
brook,  and  rill.  The  reason  why  the  streams 
flow  is,  that  the  earth  attracts  the  water 
from  the  mountains  and  hills,  down  into  the 
valleys  and  towards  the  sea." 

"  Well,  sir,  what  else  ?  "  said  Rollo. 

"Why,  there  would  never  be  any  more 
rain." 

"  No  more  rain !  "  exclaimed  all  the,  chil- 
dren. 

"  No,"  he  replied.     "  The  drops  of  rain  fall 


GRAVITATION.  153 

only  because  the  earth  draws  them  down  by 
its  attraction ;  and,  of  course,  if  this  attraction 
should  cease,  they  would  remain  where  they 
are." 

The  children  were  musing  a  minute  upon 
these  strange  effects,  when  Hollo  asked  if  any- 
thing else  would  happen. 

"  Why,  yes,"  said  his  father,  "  worse  dis- 
asters than  these  ;  but  I  do  not  know  wheth- 
er you  would  understand  them,  if  I  should 
explain  them." 

"  O,  try,"  said  Hollo ;  "  1  think  we  shall 
understand." 

"  Well,  let  me  think,"  said  his  father. 
•'  You  have  noticed  how  a  chaise  wheel,  on 
a  muddy  road,  in  a  wet  day,  holds  the  mud 
upon  it,  until  when  it  is  going  very  swiftly 
down  a  hill,  and  then  the  mud  flies  off  in  all 
directions." 

"  Yes,  sir,"  said  all  the  children. 

"  And  if  the  mud  did  not  stick  to  the 
wheel  pretty  tight,  it  would  be  thrown  off  at 
all  times,  even  when  the  wheel  was  going 
slow.  You  understand  this." 

"  Yes,  sir." 

"  Well,  now,  this  whole  earth,  you  all  know, 
is  whirling  around  through  space,  and  moving 


154  '   AIR. 

on  also  around  the  sun.  Arid  all  the  loose 
things  upon  the  surface  would  be  thrown 
off  at  once,  if  they  were  not  held  to  it  by  a 
strong  attraction.  If  this  attraction  were  to 
cease  suddenly,  —  whisk  !  —  away  we  should 
all  go  in  an  instant  —  rocks,  houses,  men,  ani- 
mals, all  in  confusion." 

•  "  O   father !  "   exclaimed   Hollo  ;    "  where 
should  we  go  to,  —  off  into  the  air  ?  " 

"  Not  exactly  into  the  air,  for  the  air 
would  all  fly  off,  and  be  dissipated  too ;  we 
should  fly  off  into  the  sky  somewhere,  some 
in  one  direction,  and  some  in  another.  You'd 
be  a  thousand  miles  off  from  the  earth,  almost 
before  you  would  know  it." 

"  Would  it  kill  us,  father?  "  said  Nathan. 

"  Yes,"  said  his  father.  "  I  don't  know 
that  there  would  be  any  shock  that  would 
hurt  us,  but  we  should  have  no  air  to  breathe, 
and  it  would  be  dark  and  dismal." 

"  Dark  ?  "  said  Rollo.  "  There  would  be 
the  sun." 

"  Yes,"  said  his  father,  "  there  would  be 
the  sun ;  and  the  sun  would  look  bright 
enough  when  you  looked  directly  towards  it, 
but  there  would  be  no  general  light  about 
you,  unless  there  was  air." 


GRAVITATION.  155 

The  children  all  paused  to  reflect  upon 
the  strange  results  which  their  father  had 
told  them  would  ensue  from  a  suspension  of 
the  earth's  attractive  force.  Rollo  began  to 
think  that  he  had  been  too  hasty  in  his  wish 
that  there  was  no  gravitation. 

"  But,  father,"  said  he,  "  the  houses  would 
not  go  off,  certainly  ;  —  only  the  loose  things 
would  go." 

"  Very  well ;.  houses  are  loose." 

"  O  father  !  they  are  fastened  down." 

"How  are  they  fastened  down?"  asked 
his  father. 

"  O,  they  are  nailed  — and," 

"  Not  nailed  to  the  ground,  certainly,"  said 
his  father. 

"No,"  said  Rollo,  laughing;  "but  then 
they  are  built  with  great  stones  and  mortar." 

"Yes,  but  there  is  no  mortar  under  the 
lowest  stones.  The  foundations  are  simply 
laid  upon  the  ground." 

"Well,"  rejoined  Rollo,  "I  thought  they 
were  fastened  somehow  or  other." 

"  No,"  said  his  father  ;  "  they  dig  the  cel- 
lar, and  only  just  lay  the  foundations  upon 
the  ground,  without  any  fastening.  The 
earth  holds  them  in  place." 


156 


"  Well,  father,"  said  Rollo,  "  that  is  what  1 
meant,  when  I  said  we  could  not  stand  up 
straight.  I  meant  the  houses.  I  read  in  a 
book  that  houses  would  be  blown  away,  if 
the  gravitation  did  not  hold  them  down." 

Here  Hollo's  father  had  a  hearty  laugh ; 
and  he  told  Rollo  that  he  thought  that  was 
rather  wide  shooting.  Rollo  wanted  to 
know  what  he  was  laughing  at;  and  Na- 
than asked  him  what  he  meant  by  wide 
shooting. 

"Why,"  said  he,  "Rollo,  you  undertook 
to  explain  to  us,  from  your  stores  of  knowl- 
edge, what  the  effects  of  a  suspension  of 
gravitation  would  be ;  and,  in  attempting  to 
tell  that  houses  would  be  m  danger  of  being 
blown  away,  you  came  no  nearer  than  to  tell 
us  that  boys  could  not  stand  up  straight ;  and 
that  is  what  I  call  pretty  wide  shooting." 

So  saying,  he  rose  from  his  seat,  and 
walked  away,  appearing  to  be  very  much 
amused.  James  laughed  too,  and  even  Rollo 
could  not  help  smiling  at  the  ridiculous 
figure  which  his  display  of  his  learning 
made.  As  for  Nathan,  he  continued  to  look 
grave,  and  said  he  did  not  see  that  it  was  any 
shooting  at  all. 


GRAVITATION.  157 

After  a  short  pause,  Hollo's  mother  said, 
"  So  you  see,  children,  the  cause  of  all  the 
pressure,  both  of  air  and  of  water,  and  all  the 
effects  produced  by  them,  are  the  results  of 
their  gravitation  towards  the  earth." 

"Yes,"  said  Hollo,  "I  believe  I  under- 
stand it  now." 

After  this,  Rollo  took  James  and  Nathan 
out  into  the  yard,  to  see  if  some  beans  had 
come  up,  which  he  had  been  planting  in  a 
sunny  corner  of  the  garden  the  day  before. 


QU  E  s  T i o  N  s . 

What  was  Mr.  Holiday's  apostrophe  to  the  earth? 
What  is  the  cause  of  weight?  Why  did  the  boys  wish 
that  there  was  no  gravitation  ?  What  was  the  first  evil 
consequence  which  their  father  said  would  ensue,  if  there 
was  no  gravitation  ?  What  was  the  second  evil  conse- 
quence ?  What  did  their  mother  say  after  the  conversation 
with  their  father  was  closed  ? 

14 


C  HAPTER    XI. 

AIR   IN   MOTION. 

ROLLO'S  dam,  which  he  had  made  when 
he  was  studying  the  philosophy  of  water, 
and  which  was  at  first  undermined  by  the 
pressure  of  the  water,  was  afterwards  carried 
away  by  its  momentum.  Rollo  learned,  at 
that  time,  that  water  moving  rapidly  had  a 
great  momentum  ;  and  about  this  time  he  had 
an  opportunity  of  learning  that  air,  when  in 
motion,  had  a  momentum  too,  capable  of 
producing  very  powerful  effects.  The  cir- 
cumstances of  the  case  were  as  follows  :  — 

One  morning,  towards  the  latter  part  of 
March,  Jonas,  being  out  in  the  barn,  observed 
some  indications  that  the  roof  wanted  re- 
pairs. It  had  been  strained  and  weakened 
by  the  heavy  snows  in  the  winter.  He  re- 
ported the  fact  to  Rollo 's  father,  who  said 
that  he  might  go,  the  next  day,  and  get  the 
carpenter  to  come  and  repair  it.  The  car- 


AIR    IN    MOTION.  159 

penter  lived  ten  miles  distant,  near  the  shore 
of  a  long  pond. 

When  Rollo  heard  of  this  proposed  expe- 
dition, he  wanted  to  go  too  ;  and  his  father 
gave  him  permission.  Jonas  was  going  in 
the  wagon.  He  told  Rollo,  the  evening  be- 
fore, that  he  meant  to  set  out  at  six  o'clock. 

"  But  suppose  it  looks  like  a  storm,"  said 
Rollo. 

"  Then  there  will  be  more  need  of  going," 
said  Jonas;  "for  if  the  equinoctial  storm 
comes  on  before  the  roof  is  strengthened,  it 
may  get  carried  away." 

"  What  is  the  equinoctial  storm  ? "  said 
Rollo. 

"  O,  it  is  a  great  storm,  which  comes  gen- 
erally about  this  time  of  year.  I  shouldn't 
wonder  if  it  should  come  on  to-morrow 
But  it  may  not  come  for  a  week ;  and  so  I 
hope  we  shall  have  time  to  get  the  roof 
mended  first." 

"  Does  it  look  like  a  storm  to-night  ?  " 
said  Rollo. 

"  No,  not  much,"  replied  Jonas.  '•  It  is  a 
little  hazy  in  the  south-^vest.  However,  if 
it  looks  like  a  storm  in  the  morning,  you  need 
not  go,  unless  you  choose  ;  though  I  shall." 


160 


"  I  wish  you  d  wait  till  the  storm  is  over," 
said  Rollo. 

"  No,"  said  Jonas,  "  I  had  rather  go  in  the 
storm  than  not." 

"Why?  "said  Rollo. 

"  Because,"  said  Jonas,  "  I  like  to  be  out 
in  storms.  Sometimes  it  is  very  grand." 

The  next  morning,  when  Rollo  awoke,  he 
found  that  it  was  light,  but  not  yet  sunrise. 
He  arose,  and  looked  out  of  the  window  to 
see  if  it  was  pleasant.  The  sky  was  some- 
what overcast,  but  there  was  a  little  blue  to 
be  seen,  and  Rollo  thought  that  it  would  be 
pleasant.  He  heard  a  noise  in  the  barn-yard, 
and,  looking  in  that  direction,  he  saw  Jonas 
just  leading  the  horse  out  of  the  stable.  So 
he  dressed  himself  soon,  and  went  down. 

When  he  got  ready,  he  went  down  into 
the  yard,  and  found  that  Jonas  had  got  the 
horse  harnessed,  and  everything  prepared. 
There  was  a  little  bag  of  oats  in  the  back 
part  of  the  wagon,  and  also  a  tin  pail,  with  a 
cover,  which  contained  a  luncheon.  Jonas 
fastened  the  horse  to  a  post,  and  said,  — 

"Now,  Rollo,  we'll  go  in  and  get  some 
breakfast." 


AIR    IN    MOTION.  16J 

"  I  thought  that  luncheon  was  for  break- 
fast," said  Rolio. 

"No,"  said  Jonas,  "that  is  for  dinner." 

"Shall  we  be  gone  all  the  day?"  said 
Rollo. 

"  We  may  be  gone  till  after  dinner,"  said 
Jonas,  "and  so  I  thought  I  would  be  sure." 

The  two  boys  went  into  the  house,  and 
there  they  found  that  Dorothy  had  got  some 
breakfast  ready  for  them  upon  the  kitchen 
table.  After  eating  their  breakfast,  they  got 
into  the  wagon,  and  set  out.  Jonas  first  put 
in  a  large  umbrella.  Just  as  they  were  driv- 
ing out'  of  the  yard,  the  first  beams  of  the 
morning  sun  shone  in  under  the  branches  of 
a  great  tree  in  'the  yard,  and  brightened  up 
the  tips  of  the  horses'  ears  and  the  boys'  faces. 
At  the  same  time,  a  rude  gust  of  wind  came 
around  the  corners  of  the  house,  and  slammed 
to  the  gate  of  the  front  yard. 

"  It's  going  to  be  pleasant,"  said  Rollo ; 
uthe  sun  is  coming  out." 

"I'm  not  very  sure  of  that,"  said  Jonas; 
"  the  wind  is  rising." 

"  We  start  just  at  sunrise,"  said  Rollo. 

"Yes,"  replied   Jonas,   "the  sun  always 
rises  at  six  o'clock  at  this  time  of  the  year."1 
g*  14* 


162  AIR. 

The  boys  rode  along  for  about  three  hours, 
before  they  came  to  the  carpenter's.  They 
were  obliged  to  travel  very  slow,  for  the 
roads  were  not  good.  It  is  true  that  the 
snow  was  all  gone,  and  the  frost  was  nearly 
out  of  the  ground  ;  but  there  were  many  deep 
ruts,  and  in  some  places  it  was  muddy.  The 
sun  went  into  a  cloud  soon  after  they  set  out, 
and  it  continued  overcast  all  the  morning. 
There  was  some  wind  too,  but,  as  it  was  be- 
hind them,  and  as  the  road  lay  through  woods 
and  among  sheltered  hills,  they  did  not  ob- 
serve it  much.  Jonas  said  that  there  was  a 
storm  coming  on,  but  he  thought  it  was  com- 
ing slowly. 

They  arrived  at  length  at  the  pond. 
There  was  a  little  village  there,  upon  the 
shore  of  the  pond.  The  reason  why  there 
happened  to  be  a  village  there,  was  this  :  A 
stream  of  water,  which  came  down  from 
among  the  mountains,  emptied  into  the  pond 
here,  and,  very  near  where  it  emptied,  it  fell 
over  a  ledge  of  rocks,  making  a  waterfall, 
where  the  people  had  built  some  mills. 
Now,  where  there  are  mills,  there  must  gen- 
erally be  a  blacksmith's  shop,  to  mend  the 
iron  work  when  it  gets  broken,  and  to  repair 


AIR    IN    MOTION.  163 

tools.  There  is  often  a  tavern,  also,  for  the 
people  who  come  to  the  mills;  and  then 
there  is  generally  a  store  or  two  ;  for  wher- 
ever people  have  to  come  together,  for  any 
business,  there  is  a  good  place  to  open  a 
store,  to  sell  them  what  they  want  to  buy. 
Thus  there  was  a  little  village  about  these 
mills,  which  was  generally  called  the  Mill 
village. 

Jonas  inquired  where  the  carpenter  lived, 
and  then  drove  directly  to  his  house.  He 
found  that  he  was  not  at  home.  He  had 
gone  across  the  pond,  to  mend  a  bridge, 
which  had  been  in  part  carried  away  by  the 
floods  made  when  the  snow  went  off.  Hollo 
sat  in  the  wagon  in  the  yard  by  the  side  of 
the  carpenter's  house,  while  Jonas  stood  at 
the  door,  making  inquiries  and  getting  this 
information. 

"  If  you  want  to  see  him  very  much,"  said 
the  carpenter's  wife,  "  I  presume  you  can  get 
a  boat  down  in  the  village,  and  go  across  the 
pond." 

"  How  far  is  he  from  the  other  side  of  the 
pond  ? " 

"  O,  close  by  the  upper  landing,"  said  she  ; 


164  JUH. 

"  not  a  quarter  of  a  mile  from  the  shore,  right 
up  the  road." 

Jonas  thanked  the  woman  for  her  informa- 
tion, and  got  into  the  wagon. 

"  Let  us  get  a  boat  and  go  over,  Jonas," 
said  Hollo,  as  they  were  turning  the  wagon 
round. 

"  I  should,"  said  Jonas,  "if  there  was  not 
such  a  threatening  of  a  storm." 

"  It  does  not  blow  much,"  said  Rollo. 

"  No,"  said  Jonas,  "  not  much  now,  but 
the  wind  may  rise  before  we  get  back. 
However,  we'll  go  and  see  if  we  can  get  a 
boat." 

After  some  inquiry,  they  found  a  boat,  at 
a  little  distance  out  of  the  village,  in  a  sort 
of  cove,  where  there  was  a  fine,  sandy  beach. 
The  boat  was  of  very  good  size,  and  it  had 
in  it  two  oars  and  a  paddle.  Jonas  looked 
out  upon  the  water,  and  up  to  the  sky,  and 
lie  listened  to  hear  the  moaning  of  the  wind 
upon  the  tops  of  the  trees.  He  wanted  very 
much  to  persevere  in  his  effort  to  find  the 
carpenter;  but  then,  on  the  other  hand,  ho 
was  not  sure  that  it  was  quite  safe  to  take  ' 
Rollo  out  upon  the  water  at  such  a  time 


AIR    IN    MOTION.  167 

He  sat  upon  a  log  upon  the  shore  a  few 
minutes,  and  seemed  lost  in  thought. 

At  last  he  said,  — 

"  Well,  Hollo,  I  believe  we'll  go.  The 
worst  that  will  happen  will  be,  that  you  may 
get  frightened  a  little.  We  can't  get  hurt." 

"  Why  can't  we  get  hurt  ?  "  said  Rollo. 

"  Why,  even  if  it  comes  on  to  blow  hard, 
it  will  probably  be  a  steady  gale,  and  I  can 
run  before  it,  if  I  can't  do  anything  else. 
And  there  can't  be  much  of  a  sea  in  this 
pond." 

Rollo  did  not  know  what  Jonas  meant 
by  much  of  a  sea  in  the  pond ;  but,  as  Jonas 
immediately  went  to  work  taking  the  horse 
out  of  the  wagon,  Rollo  did  not  ask  any 
questions.  The  boys  unharnessed  the  horse, 
for  Jonas  said  he  would  stand  easier  out  of 
harness,  and  they  might  be  gone  more  than 
an  hour.  They  fastened  him  then  to  a  tree, 
and  poured  the  oats  down  before  him  upon 
the  ground.  Then  Jonas  helped  Rollo  into  the 
boat,  and  put  in  the  tin  pail  containing  their 
luncheon,  and  also  the  umbrella ;  though  he 
said  he  did  not  think  it  would  rain  before 
they  got  back.  Then  he  shoved  off  the  boat, 
and  jumped  in  himself;  and  very  soon  they 


168 


were  gliding  smoothly  along  out  of  the 
cove. 

Rollo  wanted  to  row  ;  and  so  Jonas  let 
him  take  one  oar,  while  he  himself  sat  in  the 
stern  with  the  paddle.  Rollo  soon  learned 
the  proper  motion,  so  that  his  efforts  assist- 
ed considerably  in  propelling  the  boat. 
They  found,  when  they  were  out  at  a  little 
distance  upon  the  water,  that  the  wind  blew 
much  harder  than  Rollo  had  expected. 

"Jonas,"  said  he,  "the  wind  blows  more 
here  than  it  did  upon  the  shore." 

"  No,"  said  Jonas,  "  only  we  feel  it  more 
here  than  when  we  were  under  the  lee  of 
the  land." 

"What  do  you  mean  by  the  lee  of  the 
land  ?  "  said  Rollo. 

"  I  mean  the  shelter  of  it,"  replied  Jonas 
"Whenever  a  ship  at  sea  is  sheltered  by 
anything,  they  say  the  ship  is  under  its 
lee." 

The  boys  went  on,  Rollo  rowing,  and 
Jonas  paddling  behind,  until  at  length  Rollo 
got  tired.  Jonas  then  told  him  to  spread  the 
umbrella,  and  hold  it  up  for  a  sail.  Rollo 
did  so.  The  wind  was  blowing  pretty 
nearly  in  the  direction  in  which  they  wen. 


AIR    IN    MOTION.  lOJ 

going,  and,  by  its  impulse  upon  the  umbrella, 
it  caused  it  to  pull  very  hard.  Rollo  rested 
the  middle  of  the  handle  of  the  umbrella 
upon  his  shoulder,  holding  the  crook  in  his 
hand,  turning  it  in  such  a  position  as  to  pre- 
sent the  open  part  of  the  umbrella  fairly  to 
the  wind.  Jonas  continued  to  paddle,  and 
so  they  went  on  very  prosperously  until  thev 
had  got  two  thirds  across  the  pond,  when 
Jonas  ordered  Rollo  to  take  in  sail. 

"  Why,"  said  Rollo,  "  we  have  not  got 
across  yet." 

"No."  replied  Jonas,  "but  the  wind  is 
taking  us  out  of  our  course." 

Rollo  drew  down  the  umbrella,  and  looked 
around.  They  were  still  at  a  considerable 
distance  from  the  shore.  Jonas  extended 
his  paddle  out  into  the  water  as  far  as  he 
could  reach,  and  then  drew  it  in  towards  him 
with  several  quick  and  strong  strokes,  as  if 
he  were  endeavoring  to  pull  the  stern  of  the 
boat,  in  which  he  was  sitting,  round. 

"  What  are  you  doing  so  for  ?  "  said  Rollo. 

"  I  am  trying  to  bring  her  up  into  the 
wind,"  replied  Jonas. 

"  What  is  that  for  ?  "  asked  Rollo. 

''Why,  we've  drifted  to  leeward,"  said 
A  15 


170  AIR. 

Jonas,  "  and  I  must  bring  her  up  ;  for  we 
want  to  land  around  behind  that  point  on  the 
starboard  bow." 

Rollo  did  not  understand  Jonas's  tec!  nical 
language  very  well.  He  particularly  did  not 
know  what  Jonas  meant  by  bringing  her  up, 
for  it  seemed  to  him  that  the  pond  was  per- 
fectly level,  so  that  there  was  no  up  or  down 
either  way.  He  did  not  know  that,  in  sea 
language,  against  the  wind  was  always  up. 
and  with  the  wind,  down. 

Jonas  found  it  hard  to  bring  the  boat  up 
into  the  wind.  The  waves  had  begun  to  be 
pretty  large,  and  they  beat  against  the  bows 
of  the  boat,  and  some  of  the  water  dashed 
over  upon  Rollo.  The  wind  blew  quite 
heavily,  too  ;  and  now' that  they  had  changed 
their  direction  so  as  to  bring  the  wind  upon 
their  side,  it  embarrassed,  if  it  did  not  abso- 
lutely retard  their  progress.  Some  drops  of 
rain  also  began  to  fall. 

However,  by  hard  and  persevering  exertion, 
Jonas  at  length  succeeded  in  urging  the  boat 
forward  until  he  began  to  draw  nigh  to  the 
point  of  land ;  and  soon  afterwards  they 
came  under  the  shelter  of  it,  where  the 
water  was  smooth,  and  the  air  c  Dmparatively 


AIR    IN    MOTION.  171 

still.  Here  Rollo  put  in  his  oar  again,  and 
they  passed  along  close  under  a  high  shore, 
for  some  distance,  until  they  came  to  the 
landing.  Here  they  fastened  the  boat,  and 
then  began  to  walk  along  up  the  road. 

The  road  lay  through  the  woods,  and 
among  hills,  so  that  it  was  sheltered  ;  and  the 
only  indications  of  the  wind  which  the  boys 
noticed,  was  a  distant  roaring  sound  among  the 
forests.  They  came  at  length  to  the  bridge, 
where  they  found  several  workmen  busily 
engaged  in  laying  abutments  of  stone .  but 
the  carpenter  himself  was  not  there.  The 
men  told  Jonas  that  he  had  gone  about  half 
a  mile  away,  on  a  by-road,  to  select  and  cut 
some  timber  to  be  used  in  the  construction 
of  the  bridge. 

"  How  long  will  he  be  gone  ? "  asked 
Jonas. 

"  He  will  be  gone  two  or  three  hours," 
said  a  man  with  a  stone  hammer  in  his  hand 

"  What  shall  we  do  now?  "  asked  Rollo, 
addressing  Jonas,  after  a  short  pause. 

"Keep  on  until  we  find  him,"  replied 
Jonas.  "  But  you  may  stay  here  and  see 
them  build  the  bridge,  while  I  go  after  the 
carpenter." 


172 


Accordingly  Jonas  went  on,  leaving  Rollo 
seated  upon  a  bank  watching  the  work.  In 
about  three  quarters  of  an  hour,  he  returned  ; 
and  then  he  and  Rollo  went  back  to  the 
boat.  The  wind  had  all  this  time  continued 
to  increase,  though  they  were  so  much  shel- 
tered, that  they  did  not  notice  it  much. 

Jonas,  however,  observed  that  some  light, 
scudding  clouds  were  flying  across  the  sky, 
very  low,  being  apparently  far  beneath  the 
other  clouds.  When  they  reached  the  boat, 
Rollo  proposed  that  they  should  stop  and  eat 
some  luncheon ;  but  Jonas  said  that  he 
should  eat  his  with  a  better  appetite  on  the 
other  side  of  the  pond.  So  he  hastened 
Rollo  into  the  boat,  and,  taking  his  station  in 
the  stern,  he  began  to  ply  his  paddle  with 
all  his  force,  running  the  boat  along  under 
the  shelter  of  the  high  shore. 

"  There  isn't  much  wind,  Jonas,"  said 
Rollo. 

"  We  can  tell  better  when  we  come  rouud 
the  point,"  replied  Jonas. 

Rollo  observed  that  Jonas  looked  a  little 
anxious,  and  he  also  seemed  to  be  exerting 
himself  so  much  in  the  long,  steady  strokes 
of  his  paddle,  that  it  appeared  to  be  rather  an 


AIR    IN    MOTION.  173 

interruption  to  him  to  hear  and  answer 
questions.  Hollo  therefore  did  not  ta  k.  He 
found,  however,  as  he  drew  near  the  point; 
that  the  waves  were  running  by  it,  with 
great  speed  and  force,  down  the  pond.  As 
the  boat  shot  out  from  the  shelter  of  the 
point  into  this  place  of  exposure,  the  storm 
struck  them  suddenly,  with  a  blast  which 
swept  the  bows  of  the  boat  at  once  round 
oat  of  her  course,  and  dashed  the  spray  from 
the  waves  all  over  Hollo's  face  and  shoulders. 
It  was  with  great  difficulty  that  Jonas  could 
bring  the  boat  to  the  wind  again. 

He  succeeded,  however,  at  length,  and 
they  went  on,  for  some  time,  pitching  and 
tossing,  through  the  waves,  —  the  wind 
pressing  so  hard  upon  the  boat  that  it  was 
very  difficult  for  Jonas  to  make  any  head- 
way. The  wind  had  changed  its  direction, 
so  that  it  blew  now  almost  exactly  across 
their  course  ;  and  it  required  great  exertion 
for  Jonas  to  prevent  being  blown  away  down 
the  pond,  out  of  his  track  altogether. 

In  the  mean  time,  the  wind  rather  increased 

than  diminished ;  and  the  water  dashed  in 

so  much  over  the  bows  that  Hollo  had  to  dip 

it  up  with  the  cover  of  the  tin  pail,  and  pom 

15* 


174  AIR. 

it  out  over  the  side  of  the  boat  into  the 
pond  again.  They  were  going  on  in  this 
way,  both  toiling  very  laboriously,  when 
suddenly  they  began  to  hear  a  sound  like 
distant  thunder,  somewhat  louder  than  the 
ordinary  roaring  of  the  wind.  They  both 
looked  towards  the  shore  in  the  direction 
from  which  the  sound  came.  On  the  de- 
clivity of  a  range  of  hills  covered  with  forests 
they  saw  an  unusual  commotion  among  the 
trees.  The  tops  were  bowed  down  with 
great  force  ;  the  branches  were  broken  off, 
and  Jonas  thought  that  he  could  see  frag- 
ments of  them  flying  in  the  air ;  and  pres- 
ently, farther  down,  he  observed  several  tall 
pines  bending  over,  and  then  sinking  down 
till  they  disappeared. 

"  What  is  it  ? "  said  Rollo. 

"  A  squall,"  said  Jonas,  —  "  and  coming 
down  directly  upon  us." 

"  What  shall  we  do  ?  "  asked  Rollo. 

"  Put  the  boat  before  the  wind,"  replied 
Jonas,  "  and  let  her  run  :  we  must  go  where 
the  squall  carries  us." 

Jonas  immediately  began  to  pull  the  stern 
of  the  boat  around  with  his  paddle,  so  as  tc 
turn  the  head  of  it  away  from  the  quarter 


AIR    IN    MOTION.  175 

which  the  wind  was  blowing  from ;  and 
then  the  wind  drove  the  boat  along  very 
rapidly  over  the  waves,  which  curled  and 
foamed  on  each  side,  driving  onward  with 
great  fury.  When  they  looked  around  be- 
hind them,  they  saw  that  the  pond,  which 
was  of  a  very  dark  color,  though  spotted 
with  the  white  tips  of  the  waves  all  over  its 
surface,  was  almost  black  for  a  large  space 
in  the  direction  from  which  the  squall  was 
coming.  It  advanced  with  great  rapidity, 
and  at  last  struck  the  boat  with  a  noise  like 
thunder.  The  froth  and  foam  flew  over  the 
surface  of  the  water  like  tufts  of  cotton, 
and  the  boat  seemed  to  fly  along  the 
water  with  almost  as  much  speed  as  they  ; 
and  the  roaring  of  the  winds  and  waves  was 
so  loud  that  Rollo  had  great  difficulty  in 
making  Jonas  hear  what  he  had  to  say.  Af- 
ter a  few  minutes,  the  violence  of  the  wind 
somewhat  abated  ;  but  it  still  blew  a  steady 
and  furious  gale,  so  that  Jonas  had  to  keep 
his  boat  directly  before  it.  Thus  they  were 
driven  on,  wherever  the  wind  chose  to  carry 
them,  for  more  than  half  an  hour. 

Then  they  began  to  draw  near  the  land, 
far,  however,  very  far  from  the  place  where 


176  AIR. 

they  had  intended  to  go.  Hollo  observed 
that  Jonas  was  looking  out  very  eagerly 
towards  the  shore,  and  he  asked  him  what 
he  was  looking  for. 

"  Why,  here  we  are,"  said  Jonas,  "on  a 
lee  shore,  and  I  am  looking  out  for  a  place 
to  land." 

Rollo  looked,  and  saw  that  the  waves  were 
tumbling  with  great  violence  upon  the  rocks 
and  gravelly  beaches  which  lined  the  shore, 
and  he  was  afraid  that  the  boat  would  get 
dashed  to  pieces  upon  them.  Jonas,  however, 
observed  a  large  tree,  which  originally  stood 
upon  the  bank,  but  which  had  fallen  over, 
and  now  lay  with  its  top  partly  submerged. 
He  thought  that  this  might  afford  him  some 
shelter,  and  so  he  made  great  exertions  to 
guide  the  boat  so  as  to  bring  it  in  to  the 
shore  around  behind  this  tree.  By  means 
of  great  efforts  he  succeeded ;  and  §o  he  and 
Rollo  both  escaped  safe  to  land. 

The  boys  did  not  get  home  until  late  that 
night,  for  they  were  thrown  upon  the  shore 
nearly  two  miles  from  the  Mill  village,  and 
of  course  they  had  that  distance  to  walk. 
Jonas  was  detained  a  little  there,  too,  in 
making  arrangements  to  send  a  boy  for  the 


AIR    IN    MOTION.  177 

boat  after  the  storm  had  subsided.  When 
they  got  home,  Hollo's  father  said  that  he 
was  sorry  for  their  fatigues  and  exposures, 
but  he  was  very  glad  that  Jonas  had  perse- 
vered and  found  the  carpenter  ;  for  the  high 
wind  had  blown  down  the  back  chimney 
and  broken  the  roof  over  the  kitchen,  and 
it  was  very  necessary  to  have  it  repaired 
immediately. 


QUESTIONS. 

What  is  momentum  ?  Has  air  momentum,  when  it  is  in 
motion,  as  well  as  water  ?  At  what  time  in  the  spring  of 
the  year  does  the  sun  rise  at  six  o'clock  ?  What  did  Hollo 
think  was  the  prospect  in  respect  to  the  weather  ?  What 
did  Jonas  think  ?  What  is  meant  by  being  under  the  lee 
of  a  shore?  What  is  a  squall?  What  indications  did 
Jonas  observe  of  the  approach  of  the  squall  1  What  course 
did  he  pursue  in  order  to  avoid  the  danger  of  it  1 


CHAPTER    XII. 

AIR   AT    REST. 

A  FEW  days  after  the  adventure  described 
in  the  preceding  chapter,  Rollo  heard  his 
father  proposing  to  his  mother  that  they 
should  take  a  walk  the  next  morning  before 
breakfast.  Rollo  wanted  to  go  too.  His 
father  said  that  they  should  be  very  glad  to 
have  his  company  ;  and  he  promised  to  wake 
him  in  season. 

Rollo  felt  rather  sleepy,  when  his  father 
called  him  the  next  morning ;  but  he  jumped 
up  and  dressed  himself,*  and  was  ready  first 
of  all.  It  was  a  cool,  but  a  very  pleasant 
morning.  The  sun  was  just  coming  up. 
The  ground  in  the  path  before  the  door  was 
frozen  a  little,  and  the  air  seemed  very  still. 

When  Rollo's  mother  came  out  to  the 
door,  she  said,  — 

"  Well,  husband,  which  way  shall  we 
go?" 


AIR    AT    KEST.  179 

"  Up  on  the  rocks,"  said  Rollo ;  "let's  go 
up  on  the  rocks,  mother.  It  will  be  beauti- 
ful there  this  morning." 

"  Well,"  replied  his  mother;  "we'll  go  up 
on  the  rocks." 

The  place  which  Rollo  called  the  rocks, 
was  the  summit  of  a  rocky  hill,  which  had  a 
grassy  slope  upon  one  side,  by  which  they 
could  ascend,  and  a  precipice  of  ragged  rocks 
upon  the  other.  There  was  a  very  pleasant 
prospect  from  the  top  of  the  rocks. 

As  they  walked  along,  Rollo  said  that  it 
was  very  different  weather  that  still  morning, 
from  what  it  was  the  day  that  he  and  Jonas 
were  out  upon  the  pond. 

"Yes,"  said  his  father,  "you  had  an  op- 
portunity to  see  the  effects  of  air  in  motion 
Ihen." 

"  And  now  air  at  rest"  replied  Rollo. 

"  Pretty  nearly,"  said  his  father. 

"Yes,  sir,  entirely"  said  Rollo  ;  "there  is 
no  wind  at  .!l,  this  morning  :  hold  up  your 
hand,  and  y  ;i  can  feel." 

So  Rollo  stopped  a  moment  upon  the 
grass,  and  held  up  his  hand  to  see  whether 
there  was  any  wind. 


180  AIR. 

"  I  know  there  is  not  any  wind  that  you 
can  perceive  in  that  way,"  said  his  father. 

"How  can  we  perceive  it,  then?"  said 
Rollo. 

"  I'll  tell  you,"  replied  his  father,  "  when 
we  get  to  the  top  of  the  hill." 

They  reached  the  top  of  the  hill  soon  after 
this,  and  sat  down  upon  a  smooth  stone. 
There  was  a  very  wide  prospect  spread  out  be- 
fore them,  —  fields,  forests,  hamlets,  streams, 
—  and  here  and  there,  scattered  over  the 
landscape,  a  little  patch  of  snow.  The  sun 
was  just  up,  and  the  whole  scene  was  very 
bright  and  beautiful. 

"  Now,  father,"  said  Rollo,  "  tell  me  how 
you  know  that  there  is  any  wind  at  all." 

"  I  did  not  say  that  there  was  any  wind. 
I  said  motion  of  the  air." 

11  Why,  father,"  replied  Rollo,  "  I  thought 
that  wind  was  motion  of  the  air." 

"  So  it  is,"  said  his  father  ;  "  but  all  motion 
of  the  air  is  not  wind.  Wind  is  a  current  of 
air,  that  is,  a  progressive  motion  ;  —  and  in 
fact,  there  is,  this  morning,  a  slight  current 
from  the  westward." 

"  How  can  you  tell,  father  ?  "  asked  Rollo 


AIR    AT    REST.  181 

"  By  the  smokes  from  the  chimneys  ;  don't 
you  see  that  they  all  lean  a  little  from  the 
west  towards  the  east  ?  " 

"Not  but  a  little,  father; — and  there's 
one,  from  that  red  house,  which  goes  up 
exactly  straight." 

"  Yes,"  said  his  father,  "  there  is  one  ;  but, 
in  general,  the  columns  of  smoke  lean  ; 
which  is  proof  that  there  is  a  gentle  current 
of  air  to  the  eastward." 

"  Westward,  you  said,  father,"  rejoined 
Hollo. 

';  Yes,  from  the  westward,  but  to  the  east- 
ward. 

"  That  is  what  is  called  a  progressive 
motion,"  continued  Hollo's  father ;  "  that  is, 
the  whole  body  of  air  makes  progress ;  it 
advances  from  west  to  east.  But  there  is 
another  kind  of  motion,  called  a  vibratory 
motion." 

"  What  kind  of  a  motion  is  that,  father  ?  " 
asked  Hollo. 

"  It  is  a  very  hard  kind  to  describe,  at  any 
rate,"  said  his  father.  "It  is  a  kind  of  quiv- 
ering, which  begins  in  one  place  and  spreads 
in  every  direction.  Don't  you  hear  a  kind 
of  a  thumping  sound  ?  " 
16 


182 


"Yes,"  said  Rollo,  "a  great  way  off; 
what  is  it  ?  " 

"  Look  over  across  the  pond  there,"  said 
his  father ;  "  don't  you  see  that  man  cutting 
wood  ? " 

"  Yes,"  said  Rollo ;  "  that's  what  makes 
the  noise.  —  No,  father,"  he  continued,  after 
a  moment's  pause,  "  that's  not  it.  Look,  fa- 
ther, and  you'll  see  that  the  thumping  sound 
comes  when  his  axe  is  lifted  up." 

They  all  looked,  and  found  that  it  was  as 
Rollo  had  said.  The  strokes  of  the  axe  kept 
time,  pretty  well,  with  the  sound  of  blows, 
which  they  heard,  only  the  sounds  did  not 
correspond  with  the  descent  of  the  axe. 
When  the  axe  appeared  to  strike  the  wood, 
they  did  not  hear  any  sound,  but  they  did 
hear  one  every  time  the  axe  was  lifted  up. 

"  So,  you  see,"  said  Rollo,  "  it  is  not  that 
man  that  we  hear.  There  must  be  some 
other  man  cutting  wood." 

"  We  will  wait  a  minute,"  said  his  father, 
"  until  he  gets  the  log  cut  off,  and  then  he 
will  stop  cutting  ;  and  we  will  see  whether 
we  cease  to  hear  the  sound." 

So  they  sat  still,  and  watched  the  man  for 
a  minute.  Presently  he  stopped  cutting,  — 


AIR    AT    REST.  183 

and,  to  Hollo's  great  surprise,  the  sound 
stopped  too. 

"  That's  strange,"  said  Rollo. 

In  a  moment  more,  the  man  had  rolled  the 
log  over,  and  commenced  cutting  upon  the 
other  side ;  and  in  an  instant  after  he  began 
to  cut,  Rollo  began  to  hear  the  sound  of 
strokes  again. 

"  Yes,"  said  Rollo,  "  it  must  be  his  cut- 
ting that  we  hear ;  but  it  is  very  strange  that 
he  makes  a  noise  when  he  lifts  up  his  axe, 
and  no  noise  when  it  goes  down." 

"  I'll  tell  you  how  it  is,"  said  his  father. 
"  He  makes  'the  noise  when  his  axe  goes 
down  ;  but,  then,  it  takes  some  little  time  for 
the  sound  to  get  here  ;  and  by  the  time  the 
sound  gets  here,  his  axe  is  up." 

"  O,"  said  Rollo,  "  is  that  it  ?  " 

"Yes,"  replied  his  father,  "  that  is  it." 

Rollo  watched  the  motion  of  the  axe  sev- 
eral minutes  longer  in  silence,  and"  then  his 
attention  was  attracted  by  the  singing  of  a 
bird  upon  a  tree  in  his  father's  garden,  at  a 
short  distance  below  him. 

Pretty  soon,  however,  his  mother  said  that 
it  was  time  for  her  to  return ;  and  they  all, 


184 


accordingly,  arose  from  their  seats,  and  ram- 
bled along  together  a  short  distance  upon  the 
brow  of  the  hill,  but  towards  home. 

"  Then  the  sound  moves  along  through 
the  air,"  said  Rollo,  "from  the  man  to  us." 

"  Yes,"  said  his  father  ;  "  that  is,  there  is 
a  vibratory  motion  of  the  air,  —  a  kind  of 
quivering,  —  which  begins  where  the  man  is, 
and  spreads  all  around  in  every  direction, 
until  it  reaches  us.  But  there  is  no  progres- 
sive motion  ;  that  is,  none  of  the  air  itself, 
where  the  man  is  at  work,  leaves  him,  and 
comes  to  us." 

"But,  husband,"  said  Hollo's  mother,  "I 
don't  see  how  anything  can  come  from  where 
the  man  is,  to  us,  unless  it  is  the  air  it- 
self." 

"It  is  rather  hard  to  understand,"  said  his 
father.  "  But  I  can  make  an  experiment 
with  a  string,  when  we  get  home,  that  will 
show  you  something  about  it." 

They  rambled  about  among  the  rocks  for 
a  short  time  longer,  and  then  they  descended 
by  a  steep  and  crooked  path,  in  a  different 
place  from  where  they  had  ascended.  When 
they  had  got  nearly  home,  Rollo  said  that  lie 


AIR    AT    REST.  185 

would  run  forward  and  get  his  father's  ball 
of  twine  and  bring  it  out ;  and  so  have  it  all 
ready  for  the  experiment. 

Accordingly,  when  Hollo's  father  and 
mother  arrived  at  the  front  door,  they  found 
Rollo  ready  there  with  a  small  ball  of  twine 
in  his  hand,  about  as  large  as  an  apple. 

"  Now,  Rollo,"  said  his  father,  "  you  may 
take  hold  of  the  end  of  the  twine,  and  walk 
along  out  into  the  street,  while  I  hold  the 
ball,  and  let  the  string  unwind." 

Rollo  did  so.  He  drew  out  a  long  piece 
of  twine,  as  long  as  the  whole  front  of  the 
house,  and  then  he  stopped  to  ask  his  father 
if  that  was  enough. 

"No,"  said  his  father  ;   "  walk  along." 

So  Rollo  walked  on  for  some  distance  far- 
ther, until,  at  last,  the  ball  was  entirely  un- 
wound. Rollo  had  one  end  of  it,  and  was 
standing  at  some  distance  down  the  road, 
while  his  father,  with  the  other  end,  stood  at 
the  gate  of  the  front  yard.  The  middle  of 
the  string  hung  down  pretty  near  to  the 
ground. 

"  Draw  tight,  Rollo,"  said  his  father. 

So  Rollo  pulled  a  little    harder,  and   by 
that  means  drew  the  line  straighter. 
A*  16* 


186 


"Now,"  said  his  father,  "walk  along 
slowly." 

So  Hollo  walked  along,  drawing  the  end 
of  the  line  with  him.  His  father  followed 
with  the  other  end.  Thus  they  advanced 
several  steps  along  the  side  of  the  road. 

"  There,'f  said  his  father.  "  Stop.  That, 
you  see,  was  a.  progressive  motion." 

"  Yes,  sir,"  replied  Rollo. 

"  The  whole  string  advanced  along  the 
road,"  added  his  father.  "  It  made  progress, 
and  so  it  was  a  progressive  motion.  Now, 
fasten  your  end  of  the  string,  Rollo,  to  that 
tree  directly  behind  you." 

Rollo  looked  behind  him,  and  saw  that  he 
was  standing  near  a  small  maple-tree,  which 
had  been  planted,  a  few  years  before,  by  the 
side  of  the  road. 

"  Tie  it  right  around  the  stem  of  the  tree," 
said  his  father,  "about  as  high  as  your 
shoulder." 

Rollo  fastened  the  string  as  his  father  had 
directed.  Then  his  father  fastened  his  end, 
in  the  same  way,  to  another  tree,  which  was 
growing  near  where  he  was  standing. 

"Now,"  said  he,  "there  can  be  no  more 
progressive  motion,  but  there  can  be  a  vibra- 


AIR    AT    REST.  187 

tory  one.  Take  hold  of  the  string  near 
where  it  is  fastened  to  the  tree." 

Hollo  took  hold  of  it,  as  his  father  had 
directed,  and  then  his  father  told  him  to  shut 
his  eyes.  When  his  eyes  were  shut,  so  that 
he  could  not  see,  his  father  said  that  he  was 
going  to  strike  the  string,  at  his  end  of  it, 
with  his  pencil-case,  and  he  asked  Hollo  to 
observe  whether  he  could  feel  any  motion. 

Rollo  held  very  still,  while  his  father 
struck  the  string  ;  and  immediately  afterwards 
he  called  out,  "  Yes,  sir."  Then  his  father 
struck  the  string  again,  several  times,  and 
every  time  Rollo  could  feel  a  distinct  vibra- 
tory or  quivering  motion,  which  was  trans- 
mitted very  rapidly  through'  the  string,  from 
one  end  to  the  other ;  although,  as  the  string 
was  fastened  by  both  ends  to  the  trees,  it 
was  evident  that  there  could  be  no  progres- 
sive motion. 

Rollo's  mother  had  been  standing  all  this 
time  at  the  step  of  the  door,  watching  the 
progress  of  the  experiment ;  and,  when  she 
saw  the  expression  of  satisfaction  upon  Rol- 
lo's countenance,  while  he  was  standing, 
with  his  eyes  shut,  holding  the  end  of  the 


188  AIR. 

string,  she  wanted  to  come  and  take  hold 
of  it  herself,  so  as  to  see  what  sort  of  a  sen- 
sation the  vibratory  motion  of  the  string  pro- 
duced. 

So  she  came  out  through  the  gate,  and 
asked  Mr.  Holiday  to  wait  a  moment  while 
she  went  to  where  Rollo  was  standing,  and 
took  hold  of  the  string.  But  he  said  that  it 
would  not  be  necessary  for  her  to  go  there, 
«.s  she  could  take  hold  of  his  end  of  the 
line  just  as  well,  and  let  Rollo  strike  the 
other  end. 

They  accordingly  performed  the  experi- 
ment in  that  way,  and  Rollo's  mother  could 
feel  the  vibrations  very  distinctly. 

"One  thing  you  must  observe,"  said  Mr. 
Holiday  ;  "  and  that  is,  that  the  vibrations  pass 
along  from  one  end  of  the  line  to  the  other 
very  quick  indeed.  We  feel  them  at  one 
end  almost  at  the  same  instant  that  the  other 
end  is  struck." 

"  Exactly  at  the  same  instant,  sir,"  said 
Rollo. 

"  No,"  replied  his  father,  "  not  exactly  at 
the  same  instant,  though  it  is  very  nearly  the 
same." 


AIR    AT    REST.  189 

"  I  did  not  see  any  difference,"  said  Rollo. 

"No,"  replied  his  father,  "you  cannot 
perceive  any  difference  in  so  short  a  string , 
but  if  we  had  a  string,  or  a  wire,  a  mile  long, 
I  presume  that  we  should  find  that  it  would 
require  a  sensible  period  of  time  to  transmit 
the  vibrations  from  one  end  to  the  other." 

"  What  do  you  mean  by  a  sensible  period 
of  time,  father  ?  "  asked  Rollo. 

"  Why,  a  length  of  time  that  you  could 
perceive,"  said  his  father;  "just  as  it  was 
with  the  man  cutting  wood.  We  could  see 
that  some  time  elapsed  between  the  striking 
of  the  blow,  and  our  hearing  the  sound." 

"Yes,"  said  Rollo,  "just  as  long  as  it 
took  him  to  lift  up  his  axe." 

"  That  is  not  certain,"  replied  his  father, 
"  because  the  sound  that  we  heard  might 
have  belonged  to  a  blow  made  before.  That 
is,  it  might  be  that,  when  he  had  struck  one 
blow,  he  had  time  to  raise  his  axe  and  strike 
another,  and  then  raise  his  axe  again,  before 
the  sound  of  the  first  blow  came  to  us." 

"  Yes,  sir,"  said  Rollo,  "  I  understand." 

Mr.  Holiday  then  told  Rollo*  that  he  might 
unfasten  the  string  from  the  trees,  and  wind 
it  up  again  into  a  ball,  and  bring  it  in 


IUO 


Then  he  and  Hollo's  mother  went  into  the 
house,  to  see  if  breakfast  was  not  almost 
ready. 

That  morning,  after  they  were  all  seated 
at  the  breakfast  table,  Rollo  said  to  his  father 
that  he  did  not  exactly  understand  what 
sort  of  a  motion  the  vibratory  motion  of  the 
air  was,  after  all. 

"  No,"  said  his  father,  "  I  suppose  you  do 
not.  And,  in  fact,  I  do  not  understand  it 
very  perfectly  myself.  I  only  know  that  the 
philosophers  say,  that,  when  a  man  strikes  a 
blow  with  an  axe  upon  a  log  of  wood,  it 
produces  a  little  quivering  motion  of  the  air, 
which  spreads  all  around,  darting  off  in 
every  direction  very  swiftly.  If  a  boy 
strikes  a  tin  pail  with  a  drum-stick,  it  makes 
another  kind  of  quivering  or  vibration,  which 
is  different  from  that  which  is  made  by  the 
axe ;  but  I  don't  know  precisely  how  it 
differs.  So,  when  the  air  is  full  of  sounds, 
on  a  still  morning,  it  is  full  of  these  little 
vibrations,  like  a  string  which  trembles  from 
end  to  end,  though  its  ends  are  fastened  so 
that  it  cannot  move  away."' 

"  Then  the  air  is  never  at  rest,"  said 
Holic's  mother. 


AIK    AT    REST.  101 

"No;  certainly  not,  when  any  sound  is  to 
be  heard  ;  and  it  is  never  perfectly  silent." 

"  There  is  one  thing  very  extraordinary," 
said  Mrs.  Holiday. 

"  What  is  it  ?  "  asked  Rollo's  father. 

"  Why,  that,  when  a  great  many  sounds  are 
made  at  the  same  time,"  she  replied,  —  "as, 
for  example,  when  we  are  upon  the  top  of  a 
hill,  on  a  still  morning,  and  hear  a  great 
many  separate  sounds,  as  a  man  cutting 
wood,  birds  singing,  a  bell  ringing,  and  per- 
haps a  man  shouting  to  his  oxen, — all 
those  tremblings  or  vibrations,  being  in  the 
air  together,  do  not  interfere  with  one  an- 
other." 

"  Yes,"  said  Mr.  Holiday,  "  it  is  very  ex- 
traordinary indeed.  They  do  not  seem  to 
interfere  at  all.  When  there  are  too  many 
sounds,  or  if  there  is  a  AVind  with  them, 
they  do  interfere ;  but,  in  a  calm  morning, 
like  this,  when  the  air  is  at  rest,  you  can 
hear  a  great  many  distant  sounds  very  dis- 
tinctly." 

"  Yes,"  said  Hollo,  "  arid  I  mean  to  go  up 
to  the  top  of  the  rocks  again  after  breakfast, 
and  listen." 


192 


E  S  T  I  O  N  S  . 


What  time  of  the  year  was  it  when  Hollo  took  this  walk  ; 
How  did  Rollo  satisfy  himself  that  there  was  no  wind  at 
all  ?  How  did  his  father  prove  that  there  was  a  little 
wind  ?  Is  all  motion  of  the  air  wind  ?  What  two  kinds 
of  motion  are  mentioned  ?  What  sound  did  they  hear  ? 
What  made  Rollo  think  the  sound  was  not  made  by  the 
man  whom  they  saw  cutting  wood  ?  How  did  his  father 
explain  this  phenomenon  ?  What  experiment  did  they  try 
with  the  string  ?  Were  the  vibrations  transmitted  slowly 
or  rapidly  through  the  string  ?  Did  Rollo  think  that  he 
understood  perfectly  the  nature  of  the  vibrations  ?  What 
extraordinary  circumstance  did  Rollo's  mother  mention 
at  the  breakfast  table ? 


OF    PART    II. 


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